"Handle Unavailable Layers" does not handle a missing GRASS mapset when a vector is part of the project.

[mankoff]

Version QGIS 3.8

Summary

1. I have a QGIS project that has imported some GRASS rasters and vectors.
2. Close project
3. Delete the GRASS mapset
4. Try to open project.
5. QGIS 3.8 crashes.

If the project only has raster data, the "Handle Unavailable Layers" dialog shows up. If it has vectors, then it crashes.

QGIS and OS versions

QGIS version	3.8.3-Zanzibar	QGIS code revision	685d8b1
Compiled against Qt	5.9.5	Running against Qt	5.9.5
Compiled against GDAL/OGR	2.2.3	Running against GDAL/OGR	2.2.3
Compiled against GEOS	3.6.2-CAPI-1.10.2	Running against GEOS	3.6.2-CAPI-1.10.2 4d2925d6
PostgreSQL Client Version	10.10 (Ubuntu 10.10-0ubuntu0.18.04.1)	SpatiaLite Version	4.3.0a
QWT Version	6.1.3	QScintilla2 Version	2.10.2
PROJ.4 Version	493
OS Version	Ubuntu 18.04.3 LTS

[gioman]

duplicate #30476

[mankoff]

I'm not sure this is a duplicate. That bug report has the key phrase,

If I launch QGIS with GRASS and then open the file through the program it works.

I have no way to open the QGIS project at all.

To clarify:

1. I can add GRASS data to a project
2. I can close and re-open that project as much as I want
3. If when the project is closed, I run the script that generated the GRASS data and re-generate the data, then I can no longer open it (using the identical behavior that let me open the file before I regenerated the GRASS data).

[mankoff]

Please re-open.

[gioman]

I have no way to open the QGIS project at all.

can you share a sample project (with its sample GRASS data)?

3\. If when the project is closed, I run the script that generated the GRASS data and re-generate the data, **then** I can no longer open it (using the identical behavior that let me open the file before I regenerated the GRASS data).

the script replace the GRASS data in the location/mapset that you previously used to load data in QGIS? Can you open the GRASS data generated by your script in native GRASS?

[mankoff]

Here is an MWE that recreates this bug. I've edited the title and the initial report now that I understand it better. In summary, "Handle Missing Layers" dialog works when a GRASS mapset is removed and there were rasters in the QGIS project. If there are vectors, then it crashes.

Generate a raster in GRASS, by running each line below at a terminal:

rm -fR G
grass -c EPSG:3413 ./G
r.mapcalc "foo = 42"
r.to.vect input=foo output=foo type=point
exit

• Launch QGIS
• Navigate in browser to this folder
• Open G folder (with GRASS icon), then PERMANENT, then double-click on "foo" raster to move it to the layers panel.
• Save as 32130.qgs
• Quit QGIS

rm -fR G          # remove mapset
qgis ./32130.qgs  # Handle Unavailable Layers dialog appears

• Re-run the GRASS code above
• qgis ./32130.qgs # works!
• Add the vector layer to the mapset
• Quit QGIS

rm -fR G          # remove mapset
qgis ./32130.qgs  # CRASH