unload active plugin before updating or reinstalling it (fix #54968)

Author: alexbruy

python/pyplugin_installer/installer.py

@@ -46,7 +46,7 @@
 from qgis.core import Qgis, QgsApplication, QgsNetworkAccessManager, QgsSettings, QgsNetworkRequestParameters
 from qgis.gui import QgsMessageBar, QgsPasswordLineEdit, QgsHelp
 from qgis.utils import (iface, startPlugin, unloadPlugin, loadPlugin, OverrideCursor,
-                        reloadPlugin, updateAvailablePlugins, plugins_metadata_parser)
+                        reloadPlugin, updateAvailablePlugins, plugins_metadata_parser, isPluginLoaded)
 from .installer_data import (repositories, plugins, officialRepo,
                              settingsGroup, reposGroup, removeDir)
 from .qgsplugininstallerinstallingdialog import QgsPluginInstallerInstallingDialog
@@ -315,13 +315,21 @@ def installPlugin(self, key, quiet=False, stable=True):
             if QMessageBox.warning(iface.mainWindow(), self.tr("QGIS Python Plugin Installer"), self.tr("Are you sure you want to downgrade the plugin to the latest available version? The installed one is newer!"), QMessageBox.Yes, QMessageBox.No) == QMessageBox.No:
                 return
 
+        # if plugin is active, unload it before update, see https://github.com/qgis/QGIS/issues/54968
+        pluginWasLoaded = isPluginLoaded(plugin["id"])
+        if pluginWasLoaded:
+            unloadPlugin(plugin["id"])
+
         dlg = QgsPluginInstallerInstallingDialog(iface.mainWindow(), plugin, stable=stable)
         dlg.exec_()
 
         plugin_path = qgis.utils.home_plugin_path + "/" + key
         if dlg.result():
             error = True
             infoString = (self.tr("Plugin installation failed"), dlg.result())
+            # download failed or aborted. If plugin was active before the update, let's try to load it back
+            if pluginWasLoaded and loadPlugin(plugin["id"]):
+                startPlugin(plugin["id"])
         elif not QDir(plugin_path).exists():
             error = True
             infoString = (
@@ -612,6 +620,10 @@ def installFromZipFile(self, filePath):
 
         pluginDirectory = QDir.cleanPath(os.path.join(pluginsDirectory, pluginName))
 
+        # if plugin is active, unload it before update, see https://github.com/qgis/QGIS/issues/54968
+        if isPluginLoaded(pluginName):
+            unloadPlugin(pluginName)
+
         # If the target directory already exists as a link,
         # remove the link without resolving
         QFile(pluginDirectory).remove()