Hi, as stated in #988722 during my upgrade to Bullseye I could not cleanly migrate a postgresql cluster with a table using features from the postgis extension. Apparently the reason is that postgresql-11-postgis-2.5 and postgresql-13-postgis-3 are currently not co-installable because some dependencies of the latter are in conflict with dependencies of the former (but to migrate a cluster you need both). One is libhdf5-103-1 (which has a Breaks/Replaces on libhdf5-103) which #988722 covers and which the postgresql team is aware of. Another is gdal-data 3.2.1+dfsg-1 (but also 3.2.2+dfsg-1) which defines a Depends: on libgdal28, but also a Breaks: on libgdal20 (<< 2.5.0~) introduced with commit a029936[1]. postgresql-11-postgis-2.5 depends on libgdal20 2.4.0, but I don't think they've realized this yet.
I tried to bring this to the attention of Julien Cristau (who reassigned #988722 to hdf5) yesterday, but so far he hasn't reacted. I'd also like a second opinion/confirmation for how big of a problem this actually is. And if you deem it a problem could you make the postgresql team aware of this? Do you remember why you added that Breaks:? And if it was due to upstream changes does that mean that postgis-enabled clusters are essentially unmigratable unless you dump them in full before starting the upgrade? Because if so, this should be mentioned in the Bullseye release notes. Regards, Dennis. 1: https://salsa.debian.org/debian-gis-team/gdal/-/commit/a029936168d5b164c5943ebdcd97b417a1751829