This stopped working in calibre 4.
I run Ubuntu Mate 19.04 and I have the root fs on a NVMe drive and /home on a SATA SSD. To improve performance I have .cache on the NVMe (as /opt/.cache) and symlink that folder to ~/.cache.
I started doing this years back when I had the root fs on my first SATA SSD and /home on spinning rust. And I've kept doing it since then when the root fs is on a faster drive than /home. And it has never been any problems in any apps, including calibre. (I also have /tmp in RAM using tmpfs.)
However after upgrading to calibre 4 the calibre ebook reader can't open ebooks any more. I get this error:
/opt/.cache/calibre/ev2/t/tmpezZNaM does exist and can also be accessed via the symlink as /home/anders/.cache/calibre/ev2/t/tmpezZNaM
By moving back .cache to ~/.cache instead of symlinking, everything is fine again. I can use the new calibre viewer fine.
But if possible I would like to continue be able to place ~/.cache on the fastest drive.
https://bugs.launchpad.net/calibre/+bug/1846834