I've built various QGIS projects that use Canadian UTM and MTM CRS. They worked just fine in QGIS versions through 3.8 (based on proj4 and ?proj5).
In QGIS windows version 3.10.0-3, things got borked with the transition to proj6. QGIS version 3.10.1 seems to have largely fixed that, after I manually also installed
proj-datumgrid-north-america in OSGeo4W. My maps display fine again, with CRS conversion on the fly, without pop-up errors.
However, my QGIS message log silently displays the following, with the so-called critical errors repeating during any map redraws. (EPSG:2951 is my project CRS. It's NAD83 (CSRS) MTM zone 9.)
2019-12-11T10:39:56 CRITICAL Cannot normalize transform between EPSG:2951 and EPSG:4326 2019-12-11T10:40:04 CRITICAL Cannot normalize transform between EPSG:4326 and EPSG:2951 2019-12-11T10:40:04 CRITICAL Cannot normalize transform between EPSG:3857 and EPSG:2951 2019-12-11T10:40:04 CRITICAL Cannot normalize transform between EPSG:26918 and EPSG:2951
Now (3.10.1), the maps look normal, but I'm still surprised at critical errors, even if silent ones. Should I be worried, and if so what should I do?