Cannot save with password

[Hillbilly]

Strange problem:
Suddenly I cannot open or save a long standing calc file with a password even with basic ascii chars.
I get a "General error. General input/output error."
No pw = no problem.
I'm on OO4.1 under Linux Mint and I have reset the profile for OO.
I have also pasted the data into a new file and removed protections etc.
On the same pc with a separate disk also running Mint as a separate OS, LibreOffice works for the same file(s) on any of the 3 disks so this proves that there are no permissions issues.
Any ideas? Thanks.

[RoryOF]

Perhaps not enough free space on the troublesome drive? Extra workspace may be needed for the encryption process.

[Hillbilly]

Good point but all the drives have >100Gb spare and 16Gb RAM.
I was thinking overnight that there might be a java/python package that's gone missing. Do you know if encrypt needs a particular one?
Will try a reinstall/update/broken check next.

[Hillbilly]

None of the above cure problem.
Maybe after all these years its bye bye Open, hello Libre unless somebody has an answer.