QField Sync cable export: Failed to create MBtiles basemap

[lorenzomorning]

Hi QField community/developer,

first of all thanks for the great application that we use daily at our company! :)

With the update of QField Sync from v.4.12.2 zu 4.13.X there is the new option of assigning tile zoom levels for the automatic create of basemaps. Unfortunately, we encounter problems with the creation of basemaps during the cable export.

I am working with QGIS 3.40.4 and QFieldSync v.4.13.1 at a Windows PC. We use the cable export option as well the option of automatically creating basemaps within the export process. Unfortunately, with the mentioned update we always got the following error message for the creation of the basemap

English translation: "Could not transform extent to WGS84"

The resulting export project does not has any basemap.gpkg. I tried different zoom levels, but could not achieve any export of the basemap.

Is there a setting that I oversee or is this problem already a common one ?

Here is a test package:

QField_Test.zip

[SeqLaz]

Hi @lorenzomorning,

There is current work on fixing this: opengisch/libqfieldsync#109

For now, the workaround is to ensure the exporting folder does not contain any files, especially the "basemap.mbtiles" file.

[lorenzomorning]

@SeqLaz , that is great! I am already looking forward to it. Thanks a lot!

[suricactus]

@lorenzomorning we have fixed some of the known issues with the basemap export in the latest 4.13.2 release of the QFieldSync plugin.

Would you mind translating the error message you get from German to English?

Also, I have tried to open your sample project, but it appears empty without any layers. Only the packaged one has a few dots.

Finally, if you try to convert to mbtiles using the "Generate XYZ tiles (MBTiles)" algorithm your basemap layer, does it work as intended?

[lorenzomorning]

@suricactus thanks for your work first of all! :)
So far the new version of the plugin is not available through the official qgis plugin repository, no? In my case there is no update available so far :)

The error message means: "Could not transform the extent to WGS84". I also included this in the inital description above.

You were right. Somehow the sample project was empty. I uploaded a new version witihin the same link above. You can try it now again.

As you recommended I tried to use the QGIS tool "Generate XYZ tiles (MBTiles)" to generate a basemap layer. This also did not work for my case. The error message is the same: "Could not transform the extent to WGS84"

I also tried to set WGS84 as my new project CRS which for some reason did not work, as QGIS could not create the extents for my current layers. So I set up a complete new project within CRS WGS84 and now both worked: The QGIS tool "Generate XYZ tiles (MBTiles)" as well as the packaging via QField Sync. So the issue must be a QGIS native problem for transforming from projected CRS to the geographic CRS WGS84? :)

[suricactus]

Yes, you are right! What is your project and layer CRS? I find it weird that it cannot be transformed to WGS84.

Internally QFieldSync uses the same algorith to prepare your basemap. Therefore you got the same error.

[lorenzomorning]

Okay, that makes sense. My project and layer CRS is ETRS89 / UTM zone 32N (EPSG: 25832), so a pretty common one in Germany