I had been running LMDE 4 on my desktop for a while. It was mostly ok other than niggling issues like ethernet going off and on.
0:1f.6 Ethernet controller [0200]: Intel Corporation Ethernet Connection (2) I219-V [8086:15b8]
I had lots of pictures in HEIC from an iphone. Wanting to use ImageViewer to look at them, I read about installing heif-gdk-pixbuf . But it did not seem to be available for LMDE 4. GIMP worked to look at the files.
So I updated to LMDE 5 . After some gyrations, this completed. However, neither ImageViewer nor GIMP could open the pictures anymore.I again updated to LMDE 6. Same issue.
Perhaps this was the clue:
heif-info IMG_6553.HEIC
heif-info: error while loading shared libraries: libx265.so.165: cannot open shared object file: No such file or directory
In desperation, I downloaded and installed this from debian.
https://packages.debian.org/buster/libx265-165
After that GIMP started opening the files. Redo from start.
