QGIS 4 / Qt6 Compatibility Issues -

[osundwajeff]

QGIS 4 / Qt6 Compatibility Issues - Grouped Summary

This document groups the 47 compatibility issues by type/pattern for easier understanding.

Issue Categories

1. Build & Configuration Issues (3 issues)
2. Qt Enum Reorganizations (35 issues)
3. API Renames & Removals (3 issues)
4. Type Strictness (int -> enum) (5 issues)
5. Plugin-Specific Bugs (1 issue)

---

1. Build & Configuration Issues

Issue 1: Version Constraint Too Restrictive

File: config.json:5

qgisMaximumVersion set to 3.99.

Fix: Change to 4.99

---

Issue 2: Direct PyQt5 Import

File: gui/scenario_item_widget.py:6

Direct import from PyQt5 instead of using qgis.PyQt compatibility layer.

Fix: Use from qgis.PyQt.QtWidgets import ...

---

Issue 3: Compiled Resources Using pyrcc5

Files: admin.py:319, generated resources.py

pyrcc5 generates PyQt5-specific code, but it's deprecated in Qt6.

Fix: Resources are handled differently in Qt6.

---

2. Qt Enum Reorganizations

Pattern: Qt6 moved most enums into typed sub-namespaces.

• Qt5: Qt.AlignLeft, QDialog.Accepted, etc.
• Qt6: Qt.AlignmentFlag.AlignLeft, QDialog.DialogCode.Accepted, etc.

Possible Solution: Create file e.g. qt_compat.py with compatibility layer providing unified names for both Qt5 and Qt6.

Affected Enum Categories

A. Qt Core Enums (Issues 4, 7, 12, 16, 17, 22, 23, 24, 34, 35, 46)

Issue	Enum Type	Qt5 Example	Qt6 Namespace
4	Alignment flags	Qt.AlignLeft	Qt.AlignmentFlag.AlignLeft
7	User role	Qt.UserRole	Qt.ItemDataRole.UserRole
12	Sort order	Qt.AscendingOrder	Qt.SortOrder.AscendingOrder
16	Orientation	Qt.Horizontal	Qt.Orientation.Horizontal
17	Check state	Qt.Checked	Qt.CheckState.Checked
22	Display role	Qt.DisplayRole	Qt.ItemDataRole.DisplayRole
23	Colors	Qt.red	Qt.GlobalColor.red
24	Case sensitivity	Qt.CaseSensitive	Qt.CaseSensitivity.CaseSensitive
34	Event types	QEvent.Resize	QEvent.Type.Resize
35	Window flags	Qt.WindowMinimizeButtonHint	Qt.WindowType.WindowMinimizeButtonHint
46	Item data roles	Qt.DisplayRole	Qt.ItemDataRole.DisplayRole

Files affected: 50+ across gui/, models/, lib/
QtCompat names: AlignLeft, UserRole, SortAscending, Horizontal, CheckStateChecked, DisplayRole, ColorRed, CaseSensitive, EventResize, WindowMinimizeButtonHint

---

B. Widget Enums (Issues 8, 9, 10, 11, 15, 21, 26, 27, 28, 29, 30, 31, 32, 33, 47)

Issue	Widget Class	Qt5 Example	Qt6 Namespace
8	QToolButton	QToolButton.MenuButtonPopup	QToolButton.ToolButtonPopupMode.MenuButtonPopup
9	QSizePolicy	QSizePolicy.Fixed	QSizePolicy.Policy.Fixed
10	QAbstractItemView	QAbstractItemView.ExtendedSelection	QAbstractItemView.SelectionMode.ExtendedSelection
11	QAbstractItemView	QAbstractItemView.InternalMove	QAbstractItemView.DragDropMode.InternalMove
15	Qt Item flags	Qt.ItemIsEnabled	Qt.ItemFlag.ItemIsEnabled
21	QHeaderView	QHeaderView.Stretch	QHeaderView.ResizeMode.Stretch
26	QDialog	QDialog.Accepted	QDialog.DialogCode.Accepted
27	QWizard pixmaps	QWizard.LogoPixmap	QWizard.WizardPixmap.LogoPixmap
28	QDialogButtonBox	QDialogButtonBox.Ok	QDialogButtonBox.StandardButton.Ok
29	QFrame	QFrame.StyledPanel	QFrame.Shape.StyledPanel
30	QWizard buttons	QWizard.HelpButton	QWizard.WizardButton.HelpButton
31	Brush styles	Qt.SolidPattern	Qt.BrushStyle.SolidPattern
32	Match flags	Qt.MatchFixedString	Qt.MatchFlag.MatchFixedString
33	QItemSelectionModel	QItemSelectionModel.ClearAndSelect	QItemSelectionModel.SelectionFlag.ClearAndSelect
47	QStyle	QStyle.SP_DialogCloseButton	QStyle.StandardPixmap.SP_DialogCloseButton

Files affected: 40+ across gui/, models/
QtCompat names: MenuButtonPopup, SizePolicyFixed, SelectionExtendedSelection, DragDropInternalMove, ItemIsEnabled, HeaderStretch, DialogAccepted, WizardLogoPixmap, ButtonOk, FrameStyledPanel, WizardHelpButton, BrushSolidPattern, MatchFixedString, SelectionClearAndSelect, StyleSP_DialogCloseButton

---

C. File Dialog Enums (Issue 19)

Qt5	Qt6
QFileDialog.DontUseNativeDialog	QFileDialog.Option.DontUseNativeDialog

Files: gui/qgis_cplus_main.py, gui/activity_widget.py
QtCompat name: FileDialogDontUseNativeDialog

---

D. Network Enums (Issues 36, 37, 40, 44)

Issue	Enum Type	Qt5 Example	Qt6 Namespace
36	Network errors	QNetworkReply.NoError	QNetworkReply.NetworkError.NoError
37	Request attributes	QNetworkRequest.HttpStatusCodeAttribute	QNetworkRequest.Attribute.HttpStatusCodeAttribute
40	Known headers	QNetworkRequest.ContentTypeHeader	QNetworkRequest.KnownHeaders.ContentTypeHeader
44	Known headers	QNetworkRequest.ETagHeader	QNetworkRequest.KnownHeaders.ETagHeader

Files: api/request.py, trends_earth/api.py, trends_earth/download.py
QtCompat names: NetworkNoError, RequestHttpStatusCodeAttribute, RequestContentTypeHeader, RequestETagHeader

---

E. Other Qt Enums (Issues 38, 42)

Issue	Enum Type	Qt5 Example	Qt6 Namespace
38	QTextCursor	QTextCursor.End	QTextCursor.MoveOperation.End
42	QIODevice	QIODevice.ReadOnly	QIODevice.OpenModeFlag.ReadOnly

Files: gui/qgis_cplus_main.py, lib/reports/generator.py, gui/component_item_model.py
QtCompat names: CursorEnd, IODeviceReadOnly

---

3. API Renames & Removals

Issue 5: QStandardItem.UserType Renamed

Pattern: UserType -> UserType()
Files: 11 occurrences across gui/
Fix: Added item_user_type() helper function

---

Issue 6: QTreeWidgetItem.UserType Renamed

Pattern: UserType -> UserType()
Files: 2 occurrences
Fix: Added tree_item_user_type() helper function

---

Issue 14: QFontDatabase API Changed to Static Methods

Pattern: Instance methods -> static methods
Example: QFontDatabase().families() -> QFontDatabase.families()
Files: lib/reports/generator.py:2140,2180

---

Issue 18: Qt.ItemIsTristate Removed

Qt5: Qt.ItemIsTristate existed
Qt6: Removed entirely
Files: gui/qgis_cplus_main.py:904
Fix: Removed usage, functionality unchanged

---

Issue 25: QDialog.exec_() Renamed to exec()

Pattern: exec_() -> exec()
Reason: Python 3 no longer has exec keyword
Files: 35 occurrences across 16 files
Fix: Used sed to replace all exec_() calls

---

4. Type Strictness (int -> enum)

Pattern: QGIS 4/Qt6 APIs that previously accepted integers now require proper enum types.

Issue 20: QgsMessageLog.logMessage() Level Parameter

File: utils.py:96
Problem: level parameter rejects int, requires Qgis.MessageLevel enum
Fix: Use try/except to handle both Qgis.MessageLevel.Info (QGIS 4) and Qgis.Info (QGIS 3)

---

Issue 39: Qgis.MessageLevel Enum

File: utils.py:96-111
Problem: Similar to #20, cascading effects from int level usage
Fix: Proper enum usage with try/except fallback

---

Issue 41: QgsMessageBar.pushMessage() Level Parameter

File: gui/qgis_cplus_main.py:2805-2835
Problem: level parameter rejects int
Fix: Added int-to-enum conversion map in show_message() method:

if isinstance(level, int):
    level_map = {
        0: Qgis.MessageLevel.Info,
        1: Qgis.MessageLevel.Warning,
        2: Qgis.MessageLevel.Critical,
        3: Qgis.MessageLevel.Success,
    }
    level = level_map.get(level, level)

---

Issue 45: QgsLayoutTableColumn.setHAlignment() Requires Enum

File: models/report.py:143
Problem: When MetricColumn dataclass is deserialized from storage, alignment enum becomes int
Fix: Added int-to-enum conversion in to_qgs_column():

if isinstance(alignment, int):
    alignment_map = {
        1: QtCompat.AlignLeft,
        2: QtCompat.AlignRight,
        4: QtCompat.AlignHCenter,
    }
    alignment = alignment_map.get(alignment, QtCompat.AlignHCenter)

---

Issue 13: Qt Dock Widget Area Enums (also type strictness)

Similar pattern where DockWidgetArea enums now require proper types.

---

5. Plugin-Specific Bugs

Issue 43: Settings Enum Not Converted Before QSettings Usage

File: conf.py:318, 340-343
Problem: set_value() and get_value() converted Settings enum to .value AFTER using it in f-string
Symptom: "Empty key passed" warnings, memory corruption crash
Root cause:

# WRONG:
self.settings.setValue(f"{BASE_GROUP_NAME}/{name}", value)  # name is enum
if isinstance(name, Settings):
    name = name.value  # Too late!

# CORRECT:
if isinstance(name, Settings):
    name = name.value  # Convert BEFORE using
self.settings.setValue(f"{BASE_GROUP_NAME}/{name}", value)

Why it crashed: When enum used in f-string without .value, Python called __str__() producing "Settings.BASE_DIR" instead of "advanced/base_dir". Qt6 stricter validation led to memory corruption.

---

Summary Statistics

• Total Issues: 47
• Qt Enum Reorganizations: 35 (74%)
• API Renames: 3 (6%)
• Type Strictness: 5 (11%)
• Build/Config: 3 (6%)
• Plugin Bugs: 1 (2%)

Key Takeaways

1. Vast majority (74%) are Qt6 enum reorganizations following the same pattern
2. Single solution handles most issues: The qt_compat.py compatibility layer
3. Type strictness is new: Qt6/QGIS 4 no longer accept integers where enums are expected
4. Systematic approach works: Find enum usage -> Add to QtCompat -> Replace usage -> Test

Testing Environment

• QGIS Version: 3.99.0 Master (Qt6 build)
• Build Source: Local build from QGIS master branch
• OS: Fedora 43 Linux
• Python: 3.10.x

---

Note: For detailed information about each issue including error messages, code examples, and specific file locations, see QGIS4_COMPATIBILITY_ISSUES.

[osundwajeff]

QGIS 4 / Qt6 Compatibility Issues

Issues Discovered During Qt6 Testing

1. Version Constraint Too Restrictive

File: config.json:5

The qgisMaximumVersion is set to 3.99, which prevents QGIS 4.x from loading the plugin. QGIS 4 reads this metadata and marks the plugin as invalid/incompatible.

Error Message:

This plugin is incompatible with this version of QGIS
Plugin does not support Qt6 versions of QGIS

---

2. Direct PyQt5 Import

File: src/cplus_plugin/gui/scenario_item_widget.py:6

The file contains a direct import from PyQt5 instead of using the Qt5/Qt6 compatibility layer:

from PyQt5.QtWidgets import QWidget, QLabel, QHBoxLayout

QGIS 4 blocks direct PyQt5 imports when running on Qt6.

---

3. Compiled Resources Using pyrcc5

File: admin.py:319
Generated File: build/cplus_plugin/resources.py

The build process uses pyrcc5 to compile Qt resources, which generates PyQt5-specific code:

from PyQt5 import QtCore

Error Message:

ImportError: PyQt5 classes cannot be imported in a QGIS build based on Qt6.
Use PyQt6 or preferably the version independent qgis.PyQt import instead (where available).

Additional Context:

• pyrcc is deprecated in Qt6 and has no direct replacement
• QGIS recommends not using compiled resources for Qt6 builds
• The resources.qrc contains 4 SVG icons used with Qt resource paths (:/plugins/cplus_plugin/)
• Resource imports exist in: main.py:29, tasks.py

---

4. Qt Enum Reorganization - Alignment Flags

File: src/cplus_plugin/models/report.py:128

Qt6 reorganized enum namespaces. Alignment flags moved from Qt.AlignHCenter to Qt.AlignmentFlag.AlignHCenter.

Error Message:

AttributeError: type object 'Qt' has no attribute 'AlignHCenter'. Did you mean: 'Alignment'?

Code:

alignment: QtCore.Qt.AlignmentFlag = QtCore.Qt.AlignHCenter

Additional Context:

• This affects all Qt alignment constants (AlignLeft, AlignRight, AlignTop, AlignBottom, AlignVCenter, etc.)
• Other Qt enums may have similar namespace changes in Qt6
• Need to search for: Qt.Align*, Qt.Horizontal, Qt.Vertical, and other enum patterns
• STATUS: Fixed 1 of 23+ occurrences. Remaining occurrences being hit during runtime.

---

5. QStandardItem.UserType Renamed

Files:

• src/cplus_plugin/gui/component_item_model.py:34-36
• src/cplus_plugin/gui/metrics_builder_model.py:19-21
• src/cplus_plugin/gui/carbon_item_model.py:84

Qt6 renamed QStandardItem.UserType to QStandardItem.ItemType.UserType.

Error Message:

AttributeError: type object 'QStandardItem' has no attribute 'UserType'. Did you mean: 'ItemType'?

Code:

NCS_PATHWAY_TYPE = QtGui.QStandardItem.UserType + 2

Additional Context:

• 7 total occurrences across 3 files
• Used for defining custom item types in model/view architecture
• Qt6 returns an enum that must be converted to int: int(QStandardItem.ItemType.UserType)
• Qt5 returns an int directly

---

6. QTreeWidgetItem.UserType Renamed

Files:

• src/cplus_plugin/gui/validation/result_items.py:14-15

Qt6 renamed QTreeWidgetItem.UserType to QTreeWidgetItem.ItemType.UserType (same pattern as QStandardItem).

Error Message:

AttributeError: type object 'QTreeWidgetItem' has no attribute 'UserType'. Did you mean: 'ItemType'?

Code:

RULE_RESULT_TYPE = QtWidgets.QTreeWidgetItem.UserType + 2

Additional Context:

• 2 total occurrences in 1 file
• Same pattern as QStandardItem.UserType issue
• Requires .value to get integer: QTreeWidgetItem.ItemType.UserType.value

---

7. Qt.UserRole Reorganized

Files:

• src/cplus_plugin/gui/qgis_cplus_main.py (23 occurrences)
• src/cplus_plugin/gui/components/custom_tree_widget.py:12
• src/cplus_plugin/gui/settings/carbon_options.py:85
• src/cplus_plugin/gui/pixel_value_editor_dialog.py:65,89
• src/cplus_plugin/gui/items_selection_dialog.py:58,112

Qt6 moved Qt.UserRole to Qt.ItemDataRole.UserRole.

Error Message:

AttributeError: type object 'Qt' has no attribute 'UserRole'

Code:

SORT_ROLE = QtCore.Qt.UserRole + 2
item.setData(QtCore.Qt.UserRole, layer.get("uuid"))

Additional Context:

• 29 total occurrences across 5 files
• Very common in Model/View programming for storing custom data
• Qt6: Qt.ItemDataRole.UserRole.value
• Qt5: Qt.UserRole

---

8. QToolButton Popup Mode Enums Reorganized

Files:

• src/cplus_plugin/main.py:118
• src/cplus_plugin/gui/qgis_cplus_main.py:3063
• src/cplus_plugin/gui/constant_rasters/constant_raster_manager_dialog.py:252
• src/cplus_plugin/gui/model_component_widget.py:366

Qt6 moved QToolButton.MenuButtonPopup to QToolButton.ToolButtonPopupMode.MenuButtonPopup.

Error Message:

AttributeError: type object 'QToolButton' has no attribute 'MenuButtonPopup'

Code:

self.toolButton.setPopupMode(QToolButton.MenuButtonPopup)

Additional Context:

• 4 total occurrences across 4 files
• Affects: MenuButtonPopup, InstantPopup, DelayedPopup
• Qt6: QToolButton.ToolButtonPopupMode.MenuButtonPopup
• Qt5: QToolButton.MenuButtonPopup

---

9. QSizePolicy Enums Reorganized

Files:

• src/cplus_plugin/gui/qgis_cplus_main.py:1997
• src/cplus_plugin/gui/ncs_pwl_impact_manager_dialog.py:223,505
• src/cplus_plugin/gui/settings/priority_layer_add.py:141
• src/cplus_plugin/gui/model_description_editor.py (1 occurrence)

Qt6 moved QSizePolicy.Minimum to QSizePolicy.Policy.Minimum.

Error Message:

AttributeError: type object 'QSizePolicy' has no attribute 'Minimum'

Code:

QtWidgets.QSizePolicy.Minimum, QtWidgets.QSizePolicy.Fixed

Additional Context:

• 5 total occurrences across 4 files
• Affects: Fixed, Minimum, Maximum, Preferred, Expanding, MinimumExpanding, Ignored
• Qt6: QSizePolicy.Policy.Minimum
• Qt5: QSizePolicy.Minimum

---

10. QAbstractItemView Selection Mode Enums Reorganized

Files:

• src/cplus_plugin/gui/qgis_cplus_main.py:473

Qt6 moved QAbstractItemView.ExtendedSelection to QAbstractItemView.SelectionMode.ExtendedSelection.

Error Message:

AttributeError: type object 'QAbstractItemView' has no attribute 'ExtendedSelection'

Code:

QtWidgets.QAbstractItemView.ExtendedSelection

Additional Context:

• 1 occurrence in 1 file
• Affects: ExtendedSelection, SingleSelection, MultiSelection, NoSelection, ContiguousSelection
• Qt6: QAbstractItemView.SelectionMode.ExtendedSelection
• Qt5: QAbstractItemView.ExtendedSelection

---

11. QAbstractItemView Drag-Drop Mode Enums Reorganized

Files:

• src/cplus_plugin/gui/qgis_cplus_main.py:482
• src/cplus_plugin/gui/model_component_widget.py:374,720
• src/cplus_plugin/gui/pixel_value_editor_dialog.py:49

Qt6 moved QAbstractItemView.DropOnly to QAbstractItemView.DragDropMode.DropOnly.

Error Message:

AttributeError: type object 'QAbstractItemView' has no attribute 'DropOnly'

Code:

QtWidgets.QAbstractItemView.DropOnly

Additional Context:

• 4 occurrences across 3 files
• Affects: NoDragDrop, DragOnly, DropOnly, DragDrop, InternalMove
• Qt6: QAbstractItemView.DragDropMode.DropOnly
• Qt5: QAbstractItemView.DropOnly

---

12. Qt Sort Order Enums Reorganized

Files:

• src/cplus_plugin/gui/qgis_cplus_main.py:838,909
• src/cplus_plugin/gui/settings/cplus_options.py:988
• src/cplus_plugin/gui/settings/carbon_options.py:176

Qt6 moved Qt.AscendingOrder to Qt.SortOrder.AscendingOrder.

Error Message:

AttributeError: type object 'Qt' has no attribute 'AscendingOrder'

Code:

QtCore.Qt.AscendingOrder

Additional Context:

• 4 occurrences across 3 files
• Affects: AscendingOrder, DescendingOrder
• Qt6: Qt.SortOrder.AscendingOrder
• Qt5: Qt.AscendingOrder

---

13. Qt Dock Widget Area Enums Reorganized

Files:

• src/cplus_plugin/main.py:330,358,359

Qt6 moved Qt.NoDockWidgetArea to Qt.DockWidgetArea.NoDockWidgetArea.

Error Message:

AttributeError: type object 'Qt' has no attribute 'NoDockWidgetArea'. Did you mean: 'DockWidgetArea'?

Code:

if dock_area == Qt.NoDockWidgetArea and not self.main_widget.isFloating():
    self.iface.addDockWidget(Qt.RightDockWidgetArea, self.main_widget)

Additional Context:

• 3 occurrences in 1 file
• Affects: NoDockWidgetArea, LeftDockWidgetArea, RightDockWidgetArea, TopDockWidgetArea, BottomDockWidgetArea, AllDockWidgetAreas
• Qt6: Qt.DockWidgetArea.RightDockWidgetArea
• Qt5: Qt.RightDockWidgetArea

---

14. QFontDatabase API Changed to Static Methods

Files:

• src/cplus_plugin/utils.py:580,583

Qt6 changed QFontDatabase from instance methods to static methods. It can no longer be instantiated.

Error Message:

TypeError: QFontDatabase(a0: QFontDatabase): not enough arguments

Code (Qt5):

font_families = QtGui.QFontDatabase().families()

Code (Qt6):

font_families = QtGui.QFontDatabase.families()

Additional Context:

• 2 occurrences in 1 file
• In Qt5: QFontDatabase() creates an instance, then call methods
• In Qt6: QFontDatabase is a namespace, methods are static
• Affects: families(), addApplicationFont(), and other methods

---

15. Qt Item Flags Reorganized

Files:

• src/cplus_plugin/gui/component_item_model.py:1322
• src/cplus_plugin/gui/items_selection_dialog.py:111
• src/cplus_plugin/gui/settings/carbon_options.py:71

Qt6 moved Qt.ItemIsDropEnabled to Qt.ItemFlag.ItemIsDropEnabled.

Error Message:

AttributeError: type object 'Qt' has no attribute 'ItemIsDropEnabled'

Code:

return QtCore.Qt.ItemIsDropEnabled | flags

Additional Context:

• 3 occurrences across 3 files
• Affects all item flags: ItemIsSelectable, ItemIsEditable, ItemIsDragEnabled, ItemIsDropEnabled, ItemIsUserCheckable, ItemIsEnabled, etc.
• Qt6: Qt.ItemFlag.ItemIsDropEnabled
• Qt5: Qt.ItemIsDropEnabled

---

16. Qt Orientation Enums Reorganized

Files:

• src/cplus_plugin/gui/constant_rasters/constant_raster_manager_dialog.py:172
• src/cplus_plugin/gui/metrics_builder_model.py:682,744
• src/cplus_plugin/gui/ncs_pwl_impact_manager_dialog.py:286

Qt6 moved Qt.Horizontal to Qt.Orientation.Horizontal.

Error Message:

AttributeError: type object 'Qt' has no attribute 'Horizontal'

Code:

QtCore.Qt.Horizontal
QtCore.Qt.Vertical

Additional Context:

• 4 occurrences across 3 files
• Affects: Horizontal, Vertical
• Qt6: Qt.Orientation.Horizontal
• Qt5: Qt.Horizontal

---

17. Qt Check State Enums Reorganized

Files:

• src/cplus_plugin/gui/items_selection_dialog.py:75,90,114,136,168,183,189,196,197,198,199
• src/cplus_plugin/gui/constant_rasters/constant_raster_manager_dialog.py:472,816,931,1342

Qt6 moved Qt.Checked to Qt.CheckState.Checked.

Error Message:

AttributeError: type object 'Qt' has no attribute 'Checked'

Code:

QtCore.Qt.Checked
QtCore.Qt.Unchecked
QtCore.Qt.PartiallyChecked

Additional Context:

• 15 occurrences across 2 files
• Affects: Checked, Unchecked, PartiallyChecked
• Qt6: Qt.CheckState.Checked
• Qt5: Qt.Checked

---

18. Qt.ItemIsTristate Removed in Qt6

File:

Qt6 removed the ItemIsTristate flag from Qt.ItemFlag enum. Only ItemIsAutoTristate and ItemIsUserTristate remain.

Error Message:

AttributeError: type object 'ItemFlag' has no attribute 'ItemIsTristate'. Did you mean: 'ItemIsAutoTristate'?

Code:

ItemIsTristate = Qt.ItemFlag.ItemIsTristate  # Qt6: doesn't exist

Additional Context:

• Qt6 removed ItemIsTristate entirely from the ItemFlag enum
• Qt6 only has: ItemIsAutoTristate and ItemIsUserTristate
• Qt5 had all three: ItemIsTristate, ItemIsAutoTristate, ItemIsUserTristate
• This is a breaking API change, not just a reorganization

---

19. QFileDialog Options Reorganized

Files:

• src/cplus_plugin/ui/cplus_settings.ui:56

Qt6 moved QFileDialog.ShowDirsOnly to QFileDialog.Option.ShowDirsOnly.

Error Message:

AttributeError: type object 'QFileDialog' has no attribute 'ShowDirsOnly'

Code (in .ui XML file):

<property name="options">
    <set>QFileDialog::ShowDirsOnly</set>
</property>

Additional Context:

• 1 occurrence in cplus_settings.ui
• Error originates from setupUi() call when loading .ui file
• Fixed by removing redundant options property (widget already in GetDirectory mode)
• Qt6: QFileDialog.Option.ShowDirsOnly
• Qt5: QFileDialog.ShowDirsOnly

---

20. QgsMessageLog.logMessage() Level Parameter Type Changed

Files:

• src/cplus_plugin/trends_earth/logger.py:7

QGIS 4 changed QgsMessageLog.logMessage() to require Qgis.MessageLevel enum instead of int.

Error Message:

TypeError: QgsMessageLog.logMessage(): argument 'level' has unexpected type 'int'

Code:

# QGIS 3 (accepts int):
QgsMessageLog.logMessage(message, tag="trends.earth", level=0)

# QGIS 4 (requires enum):
QgsMessageLog.logMessage(message, tag="trends.earth", level=Qgis.MessageLevel.Info)

Additional Context:

• QGIS 3: level parameter accepts int (0=Info, 1=Warning, 2=Critical, 3=Success)
• QGIS 4: level parameter requires Qgis.MessageLevel enum
• Need to convert integer values to appropriate enum values

---

21. QHeaderView Resize Mode Enums Reorganized

Files:

• src/cplus_plugin/gui/settings/carbon_options.py:172
• src/cplus_plugin/gui/settings/cplus_options.py:980,982
• src/cplus_plugin/gui/pixel_value_editor_dialog.py:51
• src/cplus_plugin/gui/ncs_pwl_impact_manager_dialog.py:316,324,332

Qt6 moved QHeaderView.Stretch to QHeaderView.ResizeMode.Stretch.

Error Message:

AttributeError: type object 'QHeaderView' has no attribute 'Stretch'

Code:

# Qt5:
header.setSectionResizeMode(QHeaderView.Stretch)

# Qt6:
header.setSectionResizeMode(QHeaderView.ResizeMode.Stretch)

Additional Context:

• Affects: Stretch, Fixed, Interactive, ResizeToContents, Custom
• Qt6: QHeaderView.ResizeMode.Stretch
• Qt5: QHeaderView.Stretch

---

22. Qt.DisplayRole and Other ItemDataRole Enums Reorganized

Files:

• src/cplus_plugin/gui/settings/cplus_options.py (7 occurrences)
• src/cplus_plugin/gui/qgis_cplus_main.py (4 occurrences)
• src/cplus_plugin/gui/activity_editor_dialog.py (5 occurrences)
• src/cplus_plugin/gui/metrics_builder_model.py (2 occurrences)
• src/cplus_plugin/gui/financials/npv_manager_dialog.py (12 occurrences of EditRole)

Qt6 moved Qt.DisplayRole to Qt.ItemDataRole.DisplayRole (same as UserRole in Issue #7).

Error Message:

AttributeError: type object 'Qt' has no attribute 'DisplayRole'

Code:

# Qt5:
item.setData(QtCore.Qt.DisplayRole, value)

# Qt6:
item.setData(QtCore.Qt.ItemDataRole.DisplayRole, value)

Additional Context:

• Affects: DisplayRole, EditRole, ToolTipRole, StatusTipRole, DecorationRole, etc.
• Qt6: Qt.ItemDataRole.DisplayRole
• Qt5: Qt.DisplayRole
• UserRole was fixed in Issue 7, but DisplayRole and others need fixing

---

23. Qt Color Constants Reorganized (GlobalColor)

Files:

• src/cplus_plugin/gui/components/svg_label.py:49 (transparent)
• src/cplus_plugin/gui/metrics_builder_model.py:428,620 (lightGray, white)
• src/cplus_plugin/gui/financials/npv_financial_model.py:56,72 (lightGray)

Qt6 moved color constants like Qt.transparent to Qt.GlobalColor.transparent.

Error Message:

AttributeError: type object 'Qt' has no attribute 'transparent'

Code:

# Qt5:
pixmap.fill(QtCore.Qt.transparent)

# Qt6:
pixmap.fill(QtCore.Qt.GlobalColor.transparent)

Additional Context:

• Affects color constants: transparent, white, black, red, green, blue, etc.
• Qt6: Qt.GlobalColor.transparent
• Qt5: Qt.transparent

---

24. Qt Case Sensitivity Enums Reorganized

Files:

• src/cplus_plugin/gui/settings/cplus_options.py:976

Qt6 moved Qt.CaseInsensitive to Qt.CaseSensitivity.CaseInsensitive.

Error Message:

AttributeError: type object 'Qt' has no attribute 'CaseInsensitive'. Did you mean: 'CaseSensitivity'?

Code:

# Qt5:
proxy_model.setSortCaseSensitivity(Qt.CaseInsensitive)

# Qt6:
proxy_model.setSortCaseSensitivity(Qt.CaseSensitivity.CaseInsensitive)

Additional Context:

• Affects: CaseInsensitive, CaseSensitive
• Qt6: Qt.CaseSensitivity.CaseInsensitive
• Qt5: Qt.CaseInsensitive

---

25. QDialog.exec_() Renamed to exec()

Files:

• 38 occurrences across 14 files:
  • gui/settings/cplus_options.py (6 occurrences)
  • gui/qgis_cplus_main.py (7 occurrences)
  • gui/model_component_widget.py (7 occurrences)
  • gui/constant_rasters/constant_raster_manager_dialog.py (2 occurrences)
  • trends_earth/api.py (4 occurrences)
  • trends_earth/download.py (2 occurrences)
  • api/request.py, api/layer_tasks.py, api/carbon.py (1 each)
  • gui/priority_group_dialog.py, gui/priority_layer_dialog.py, gui/metrics_builder_dialog.py, gui/validation/progress_dialog.py, trends_earth/worker.py (1 each)

Qt6 renamed exec_() to exec() since Python 3 removed exec as a keyword.

Error Message:

AttributeError: 'DlgSettingsLogin' object has no attribute 'exec_'. Did you mean: 'exec'?

Code:

# Qt5:
dialog.exec_()

# Qt6:
dialog.exec()

Additional Context:

• Affects all QDialog subclasses and QEventLoop, QMenu, etc.
• Qt6: dialog.exec()
• Qt5: dialog.exec_()
• Python 2 had 'exec' as keyword, requiring underscore suffix
• Python 3 removed the keyword, so Qt6 dropped the suffix

---

26. QDialog.Accepted and QDialog.Rejected Enum Reorganization

Files:

• 12 occurrences across 5 files:
  • gui/qgis_cplus_main.py (3 occurrences)
  • gui/model_component_widget.py (5 occurrences)
  • gui/metrics_builder_dialog.py (1 occurrence)
  • gui/constant_rasters/constant_raster_manager_dialog.py (2 occurrences)

Qt6 moved QDialog result codes into the QDialog.DialogCode enum namespace.

Error Message:

AttributeError: type object 'QDialog' has no attribute 'Accepted'. Did you mean: 'accepted'?

Location Example:
model_component_widget.py:849

Code:

# Qt5:
if editor.exec() == QtWidgets.QDialog.Accepted:

# Qt6:
if editor.exec() == QtWidgets.QDialog.DialogCode.Accepted:

Additional Context:

• Affects: Accepted, Rejected dialog codes
• Qt6: QDialog.DialogCode.Accepted, QDialog.DialogCode.Rejected
• Qt5: QDialog.Accepted, QDialog.Rejected

---

27. QWizard Pixmap Enum Reorganization

Files:

• gui/metrics_builder_dialog.py (1 occurrence)

Qt6 moved QWizard pixmap constants into the QWizard.WizardPixmap enum namespace.

Error Message:

AttributeError: type object 'QWizard' has no attribute 'LogoPixmap'

Location Example:
metrics_builder_dialog.py:260

Code:

# Qt5:
self.setPixmap(QtWidgets.QWizard.LogoPixmap, ci_pixmap)

# Qt6:
self.setPixmap(QtWidgets.QWizard.WizardPixmap.LogoPixmap, ci_pixmap)

Additional Context:

• Affects: LogoPixmap, WatermarkPixmap, BannerPixmap, BackgroundPixmap
• Qt6: QWizard.WizardPixmap.LogoPixmap
• Qt5: QWizard.LogoPixmap

---

28. QDialogButtonBox StandardButton Enum Reorganization

Files:

• 14 occurrences across 8 files:
  • gui/priority_layer_dialog.py (2 occurrences - Ok)
  • gui/ncs_pwl_impact_manager_dialog.py (2 occurrences - Ok, Reset)
  • gui/priority_group_dialog.py (2 occurrences - Ok)
  • gui/model_description_editor.py (1 occurrence - Save, Cancel)
  • gui/constant_rasters/custom_type_dialog.py (1 occurrence - Ok, Cancel)
  • gui/settings/priority_layer_add.py (3 occurrences - Cancel, Ok)
  • gui/validation/progress_dialog.py (2 occurrences - Ok, Close)
  • gui/financials/npv_manager_dialog.py (1 occurrence - Ok)

Qt6 moved QDialogButtonBox button constants into the QDialogButtonBox.StandardButton enum namespace.

Error Message:

AttributeError: type object 'QDialogButtonBox' has no attribute 'Ok'

Location Example:
priority_layer_dialog.py:45

Code:

# Qt5:
self.button_box.button(QtWidgets.QDialogButtonBox.Ok)

# Qt6:
self.button_box.button(QtWidgets.QDialogButtonBox.StandardButton.Ok)

Additional Context:

• Affects: Ok, Cancel, Save, Close, Open, Reset, RestoreDefaults, Help, Apply, Discard, Yes, No, and many other standard buttons
• Qt6: QDialogButtonBox.StandardButton.Ok
• Qt5: QDialogButtonBox.Ok

---

29. QFrame Shape and Shadow Enum Reorganization

Files:

• gui/constant_rasters/constant_raster_manager_dialog.py (2 occurrences)

Qt6 moved QFrame shape and shadow constants into separate enum namespaces: QFrame.Shape and QFrame.Shadow.

Error Message:

AttributeError: type object 'QFrame' has no attribute 'StyledPanel'

Location Example:
constant_raster_manager_dialog.py:97

Code:

# Qt5:
info_banner.setFrameShape(QtWidgets.QFrame.StyledPanel)
info_banner.setFrameShadow(QtWidgets.QFrame.Raised)

# Qt6:
info_banner.setFrameShape(QtWidgets.QFrame.Shape.StyledPanel)
info_banner.setFrameShadow(QtWidgets.QFrame.Shadow.Raised)

Additional Context:

• Frame shapes: NoFrame, Box, Panel, StyledPanel, HLine, VLine, WinPanel
• Frame shadows: Plain, Raised, Sunken
• Qt6: QFrame.Shape.StyledPanel, QFrame.Shadow.Raised
• Qt5: QFrame.StyledPanel, QFrame.Raised

---

30. QWizard Button Enum Reorganization

Files:

• gui/metrics_builder_dialog.py (1 occurrence)

Qt6 moved QWizard button constants into the QWizard.WizardButton enum namespace.

Error Message:

AttributeError: type object 'QWizard' has no attribute 'HelpButton'. Did you mean: 'setButton'?

Location Example:
metrics_builder_dialog.py:262

Code:

# Qt5:
help_button = self.button(QtWidgets.QWizard.HelpButton)

# Qt6:
help_button = self.button(QtWidgets.QWizard.WizardButton.HelpButton)

Additional Context:

• Affects: BackButton, NextButton, CommitButton, FinishButton, CancelButton, HelpButton, CustomButton1, CustomButton2, CustomButton3
• Qt6: QWizard.WizardButton.HelpButton
• Qt5: QWizard.HelpButton

---

31. Qt Brush Style Enum Reorganization

Files:

• 5 occurrences across 2 files:
  • gui/metrics_builder_model.py (3 occurrences - SolidPattern, NoBrush)
  • gui/financials/npv_financial_model.py (2 occurrences - SolidPattern)

Qt6 moved brush style constants into the Qt.BrushStyle enum namespace.

Error Message:

AttributeError: type object 'Qt' has no attribute 'SolidPattern'

Location Example:
metrics_builder_model.py:429

Code:

# Qt5:
background.setStyle(QtCore.Qt.SolidPattern)

# Qt6:
background.setStyle(QtCore.Qt.BrushStyle.SolidPattern)

Additional Context:

• Affects: NoBrush, SolidPattern, Dense1Pattern through Dense7Pattern, HorPattern, VerPattern, CrossPattern, BDiagPattern, FDiagPattern, DiagCrossPattern, LinearGradientPattern, RadialGradientPattern, ConicalGradientPattern, TexturePattern
• Qt6: Qt.BrushStyle.SolidPattern
• Qt5: Qt.SolidPattern

---

32. Qt Match Flag Enum Reorganization

Files:

• 6 occurrences across 4 files:
  • gui/metrics_builder_model.py (1 occurrence - MatchFixedString)
  • gui/qgis_cplus_main.py (1 occurrence - MatchExactly)
  • gui/settings/cplus_options.py (2 occurrences - MatchExactly)
  • gui/activity_editor_dialog.py (2 occurrences - MatchExactly)

Qt6 moved match flag constants into the Qt.MatchFlag enum namespace.

Error Message:

AttributeError: type object 'Qt' has no attribute 'MatchFixedString'

Location Example:
metrics_builder_model.py:325

Code:

# Qt5:
items = self.findItems(name, QtCore.Qt.MatchFixedString)

# Qt6:
items = self.findItems(name, QtCore.Qt.MatchFlag.MatchFixedString)

Additional Context:

• Affects: MatchExactly, MatchFixedString, MatchContains, MatchStartsWith, MatchEndsWith, MatchRegExp, MatchWildcard, MatchCaseSensitive, MatchRecursive
• Qt6: Qt.MatchFlag.MatchFixedString
• Qt5: Qt.MatchFixedString

---

33. QItemSelectionModel SelectionFlag Enum Reorganization

Files:

• 3 occurrences across 3 files:
  • gui/metrics_builder_dialog.py (1 occurrence - ClearAndSelect)
  • gui/model_component_widget.py (1 occurrence - Deselect)
  • gui/financials/npv_manager_dialog.py (1 occurrence - ClearAndSelect)

Qt6 moved QItemSelectionModel selection flag constants into the QItemSelectionModel.SelectionFlag enum namespace.

Error Message:

AttributeError: type object 'QItemSelectionModel' has no attribute 'ClearAndSelect'

Location Example:
metrics_builder_dialog.py:1214

Code:

# Qt5:
selection_model.select(index, QtCore.QItemSelectionModel.ClearAndSelect)

# Qt6:
selection_model.select(index, QtCore.QItemSelectionModel.SelectionFlag.ClearAndSelect)

Additional Context:

• Affects: NoUpdate, Clear, Select, Deselect, Toggle, Current, Rows, Columns, ClearAndSelect, SelectCurrent
• Qt6: QItemSelectionModel.SelectionFlag.ClearAndSelect
• Qt5: QItemSelectionModel.ClearAndSelect

---

34. QEvent Type Enum Reorganization

Files:

• 2 occurrences across 2 files:
  • gui/metrics_builder_dialog.py (1 occurrence - Resize)
  • gui/financials/npv_manager_dialog.py (1 occurrence - Resize)

Qt6 moved QEvent type constants into the QEvent.Type enum namespace.

Error Message:

AttributeError: type object 'QEvent' has no attribute 'Resize'

Location Example:
metrics_builder_dialog.py:1452

Code:

# Qt5:
if event.type() == QtCore.QEvent.Resize:

# Qt6:
if event.type() == QtCore.QEvent.Type.Resize:

Additional Context:

• Affects: All event types including Resize, KeyPress, MouseButtonPress, Paint, Close, Show, Hide, Enter, Leave, FocusIn, FocusOut, etc.
• Qt6: QEvent.Type.Resize
• Qt5: QEvent.Resize

---

35. Qt Window Flag Enum Reorganization

Files:

• 3 occurrences across 3 files:
  • gui/validation/inspector_dialog.py (1 occurrence - WindowMinimizeButtonHint)
  • gui/progress_dialog.py (1 occurrence - WindowMinimizeButtonHint, WindowCloseButtonHint)
  • gui/qgis_cplus_main.py (1 occurrence - WindowModal)

Qt6 moved window flag and modality constants into separate enum namespaces.

Error Message:

type object 'Qt' has no attribute 'WindowMinimizeButtonHint'

Location Example:
validation/inspector_dialog.py:36

Code:

# Qt5:
flags = self.windowFlags() | QtCore.Qt.WindowMinimizeButtonHint

# Qt6:
flags = self.windowFlags() | QtCore.Qt.WindowType.WindowMinimizeButtonHint

Additional Context:

• Window flags: WindowMinimizeButtonHint, WindowMaximizeButtonHint, WindowCloseButtonHint, WindowStaysOnTopHint, WindowTitleHint, etc.
• Modality: WindowModal, ApplicationModal, NonModal
• Qt6: Qt.WindowType.WindowMinimizeButtonHint
• Qt5: Qt.WindowMinimizeButtonHint

---

36. QNetworkReply NetworkError Enum Reorganization

Files:

• 2 occurrences in 1 file:
  • api/request.py (2 occurrences - NoError)

Qt6 moved QNetworkReply error constants into the QNetworkReply.NetworkError enum namespace.

Error Message:

type object 'QNetworkReply' has no attribute 'NoError'

Location Example:
api/request.py:507

Code:

# Qt5:
if reply.error() == QNetworkReply.NoError:

# Qt6:
if reply.error() == QNetworkReply.NetworkError.NoError:

Additional Context:

• Affects: NoError, ConnectionRefusedError, RemoteHostClosedError, HostNotFoundError, TimeoutError, OperationCanceledError, and all other network error codes
• Qt6: QNetworkReply.NetworkError.NoError
• Qt5: QNetworkReply.NoError

---

37. QNetworkRequest Attribute Enum Reorganization

Files:

• 2 occurrences across 2 files:
  • api/request.py (1 occurrence - HttpStatusCodeAttribute)
  • trends_earth/api.py (1 occurrence - HttpStatusCodeAttribute)

Qt6 moved QNetworkRequest attribute constants into the QNetworkRequest.Attribute enum namespace.

Error Message:

type object 'QNetworkRequest' has no attribute 'HttpStatusCodeAttribute'

Location Example:
api/request.py:510

Code:

# Qt5:
http_status = reply.attribute(QNetworkRequest.HttpStatusCodeAttribute)

# Qt6:
http_status = reply.attribute(QNetworkRequest.Attribute.HttpStatusCodeAttribute)

Additional Context:

• Affects: HttpStatusCodeAttribute, RedirectionTargetAttribute, ConnectionEncryptedAttribute, and all other request attributes
• Qt6: QNetworkRequest.Attribute.HttpStatusCodeAttribute
• Qt5: QNetworkRequest.HttpStatusCodeAttribute

---

38. QTextCursor MoveOperation Enum Reorganization

Files:

• 1 occurrence in 1 file:
  • gui/qgis_cplus_main.py (1 occurrence - End)

Qt6 moved QTextCursor move operation constants into the QTextCursor.MoveOperation enum namespace.

Error Message:

AttributeError: type object 'QTextCursor' has no attribute 'End'

Location Example:
gui/qgis_cplus_main.py:379

Code:

# Qt5:
log_text_cursor.movePosition(QtGui.QTextCursor.End)

# Qt6:
log_text_cursor.movePosition(QtGui.QTextCursor.MoveOperation.End)

Additional Context:

• Affects: NoMove, Start, End, Up, Down, Left, Right, StartOfLine, EndOfLine, StartOfBlock, EndOfBlock, and all other cursor movement operations
• Qt6: QTextCursor.MoveOperation.End
• Qt5: QTextCursor.End

---

39. Qgis.MessageLevel Enum Reorganization

Files:

• 1 occurrence in 1 file:
  • utils.py (log function - Info, Warning)

QGIS 4 moved message level constants into the Qgis.MessageLevel enum namespace.

Error Message:

TypeError: unable to convert a C++ 'Qgis::MessageLevel' instance to a Python object

Location Example:
utils.py:96

Code:

# QGIS 3:
level = Qgis.Info if info else Qgis.Warning

# QGIS 4:
level = Qgis.MessageLevel.Info if info else Qgis.MessageLevel.Warning

Additional Context:

• Affects: Info, Warning, Critical, Success, NoLevel
• QGIS 4: Qgis.MessageLevel.Info
• QGIS 3: Qgis.Info
• Used try/except for backward compatibility

---

40. QNetworkRequest KnownHeaders Enum Reorganization

Files:

• 3 occurrences across 2 files:
  • api/request.py (2 occurrences - ContentTypeHeader, ContentLengthHeader)
  • trends_earth/api.py (1 occurrence - ContentTypeHeader)

Qt6 moved QNetworkRequest header constants into the QNetworkRequest.KnownHeaders enum namespace.

Error Message:

type object 'QNetworkRequest' has no attribute 'ContentTypeHeader'

Location Example:
api/request.py:731

Code:

# Qt5:
request.setHeader(QNetworkRequest.ContentTypeHeader, "application/json")

# Qt6:
request.setHeader(QNetworkRequest.KnownHeaders.ContentTypeHeader, "application/json")

Additional Context:

• Affects: ContentTypeHeader, ContentLengthHeader, LocationHeader, LastModifiedHeader, CookieHeader, SetCookieHeader, UserAgentHeader, ServerHeader, etc.
• Qt6: QNetworkRequest.KnownHeaders.ContentTypeHeader
• Qt5: QNetworkRequest.ContentTypeHeader

---

41. QgsMessageBar.pushMessage() Level Parameter Type Change

Files:

• 1 file updated:
  • gui/qgis_cplus_main.py (show_message method)

QGIS 4 requires QgsMessageBar.pushMessage() level parameter to be a proper Qgis.MessageLevel enum, not an integer.

Error Message:

TypeError: QgsMessageBar.pushMessage(): arguments did not match any overloaded call:
  overload 1: argument 'level' has unexpected type 'int'

Location Example:
gui/qgis_cplus_main.py:2818

Code:

# Fixed: Added conversion logic in show_message method
# to ensure level is always proper MessageLevel enum
if isinstance(level, int):
    level_map = {
        0: Qgis.MessageLevel.Info if hasattr(Qgis, 'MessageLevel') else Qgis.Info,
        # ... etc
    }

Additional Context:

• Similar to Issue 39 but for QgsMessageBar instead of QgsMessageLog
• Added default parameter handling and int-to-enum conversion
• Maintains backward compatibility with QGIS 3

---

42. QIODevice OpenModeFlag Enum Reorganization

Files:

• 3 occurrences across 2 files:
  • lib/reports/generator.py (1 occurrence - ReadOnly)
  • gui/component_item_model.py (2 occurrences - ReadOnly, WriteOnly)

Qt6 moved QIODevice open mode flags into the QIODevice.OpenModeFlag enum namespace.

Error Message:

AttributeError: type object 'QIODevice' has no attribute 'ReadOnly'

Location Example:
lib/reports/generator.py:2380

Code:

# Qt5:
template_file.open(QtCore.QIODevice.ReadOnly)

# Qt6:
template_file.open(QtCore.QIODevice.OpenModeFlag.ReadOnly)

Additional Context:

• Affects: NotOpen, ReadOnly, WriteOnly, ReadWrite, Append, Truncate, Text, Unbuffered
• Qt6: QIODevice.OpenModeFlag.ReadOnly
• Qt5: QIODevice.ReadOnly

---

43. Settings Enum Not Converted to Value Before QSettings Usage

File: conf.py:318, 340-343

The set_value() and get_value() methods in SettingsManager were converting Settings enum to .value AFTER using it in the QSettings key string, causing malformed setting keys.

Error Message:

Warning: QSettings::value: Empty key passed
malloc(): unsorted double linked list corrupted

Location:

• conf.py:318 - set_value() method
• conf.py:340-343 - get_value() method

Code:

# Before (WRONG order):
def set_value(self, name: str, value):
    self.settings.setValue(f"{self.BASE_GROUP_NAME}/{name}", value)  # Uses enum here
    if isinstance(name, Settings):
        name = name.value  # Converts AFTER using it

# After (CORRECT order):
def set_value(self, name: str, value):
    if isinstance(name, Settings):
        name = name.value  # Convert BEFORE using it
    self.settings.setValue(f"{self.BASE_GROUP_NAME}/{name}", value)

Additional Context:

• When Settings enum was used in f-string without .value, Python called __str__() on the enum
• This produced malformed keys like "cplus/Settings.BASE_DIR" instead of "cplus/advanced/base_dir"
• Qt6 appears more strict about empty or malformed QSettings keys, leading to memory corruption
• The crash manifested as "malloc(): unsorted double linked list corrupted"
• Both get_value() and set_value() had this issue
• Not strictly a Qt6-only issue, but Qt6's stricter validation exposed it as a crash

---

44. QNetworkRequest.ETagHeader Missing from Known Headers

File: trends_earth/download.py:122

Qt6 moved ETagHeader into the QNetworkRequest.KnownHeaders enum namespace.

Error Message:

AttributeError: type object 'QNetworkRequest' has no attribute 'ETagHeader'. Did you mean: 'rawHeader'?

Location:
trends_earth/download.py:122

Code:

# Qt5:
expected = h.header(QtNetwork.QNetworkRequest.ETagHeader).strip('"')

# Qt6:
expected = h.header(QtCompat.RequestETagHeader).strip('"')

Additional Context:

• Part of QNetworkRequest.KnownHeaders enum
• Qt6: QNetworkRequest.KnownHeaders.ETagHeader
• Qt5: QNetworkRequest.ETagHeader
• Only 1 occurrence in the codebase

---

45. QgsLayoutTableColumn.setHAlignment() Requires Enum Not Int

File: models/report.py:143

QGIS 4 requires QgsLayoutTableColumn.setHAlignment() to receive a proper Qt.AlignmentFlag enum instead of an integer.

Error Message:

TypeError: QgsLayoutTableColumn.setHAlignment(): argument 1 has unexpected type 'int'

Location:
models/report.py:143 in MetricColumn.to_qgs_column()

Code:

# Before:
layout_column.setHAlignment(self.alignment)  # alignment might be int

# After (with conversion):
alignment = self.alignment
if isinstance(alignment, int):
    alignment_map = {
        1: QtCompat.AlignLeft,
        2: QtCompat.AlignRight,
        4: QtCompat.AlignHCenter,
    }
    alignment = alignment_map.get(alignment, QtCompat.AlignHCenter)
layout_column.setHAlignment(alignment)

Additional Context:

• When MetricColumn dataclass is deserialized from storage, alignment enum becomes int
• QGIS 3 accepted int values, QGIS 4 requires proper Qt.AlignmentFlag enum
• Similar to Issue 41 (QgsMessageBar.pushMessage level parameter)
• Added int-to-enum conversion in to_qgs_column() method
• Common alignment values: AlignLeft (1), AlignRight (2), AlignHCenter (4)

---

46. Qt.DisplayRole Enum Reorganization

Files:

• 2 occurrences across 2 files:
  • lib/reports/generator.py:1778
  • lib/reports/layout_items.py:323

Qt6 moved Qt.DisplayRole into the Qt.ItemDataRole enum namespace.

Error Message:

AttributeError: type object 'Qt' has no attribute 'DisplayRole'

Location Example:
lib/reports/generator.py:1778

Code:

# Qt5:
node_name = str(child_node.data(QtCore.Qt.DisplayRole))

# Qt6:
node_name = str(child_node.data(QtCompat.DisplayRole))

Additional Context:

• Qt6: Qt.ItemDataRole.DisplayRole
• Qt5: Qt.DisplayRole
• Other item data roles already in QtCompat: UserRole, EditRole, ToolTipRole, StatusTipRole, DecorationRole
• This was a simple find-and-replace to use existing QtCompat compatibility layer

---

47. QStyle.SP_DialogCloseButton Enum Reorganization

Files:

• 2 occurrences in 1 file:
  • gui/progress_dialog.py:286, 428

Qt6 moved QStyle standard pixmap constants into the QStyle.StandardPixmap enum namespace.

Error Message:

AttributeError: type object 'QStyle' has no attribute 'SP_DialogCloseButton'

Location Example:
gui/progress_dialog.py:286

Code:

# Qt5:
icon = self.style().standardIcon(QStyle.SP_DialogCloseButton)

# Qt6:
icon = self.style().standardIcon(QtCompat.StyleSP_DialogCloseButton)

Additional Context:

• Qt6: QStyle.StandardPixmap.SP_DialogCloseButton
• Qt5: QStyle.SP_DialogCloseButton

---

Testing Environment

• QGIS Version: 3.99.0 Master (Qt6 build)
• Build Source: Local build from QGIS master branch
• OS: Fedora 43 Linux
• Python: 3.10.x