Server: New added permissions got lost on every nextcloud restart

[tcg71]

Steps to reproduce
(still working on new installed system)
Create folder (or use existing)
Share with additional local user or group (email/link share is persistant) ->Check: new share is usable by added user/group
Restart nextcloud

Expected behaviour
Newly added share permissions should be persistant to nextcloud restarts

Actual behaviour
Only previous share permissions (before August 2020 - maybe until 18.0.x) are active/visible (changes are not persistant)

Server configuration
OS: Ubuntu 20.04 64Bit Linux 5.4.0-51-generic
Official Snap latest/stable: 19.0.4snap1 2020-10-14 (23743)
Was first recognized on 19.0.1, on Ubuntu 18.04, but maybe still older

[skjnldsv]

Are you sure there isn't an issue with your database?
Can you export the share table before and after reboot?
Can you see your share in here?

[tcg71]

Looks like the database entry got lost on restart. Right before restart I added a new share (so it's the last entry).

Last entries of oc_share (from dump before and after restart - , and are used for user- and foldernames):

• Before restart:
  (3084,2,'<user1>','<admin1>','<admin1>',393,'folder','149580',NULL,149580,'<folder1>',1,1558082285,0,NULL,NULL,0,NULL,NULL,0,NULL,0,NULL), (3086,0,'<user2>','<admin1>','<admin1>',0,'folder','86905',NULL,86905,'<folder2>',15,1603208219,1,NULL,NULL,0,NULL,NULL,0,NULL,0,NULL);
• After restart:
  (3084,2,'<user1>','<admin1>','<admin1>',393,'folder','149580',NULL,149580,'<folder1>',1,1558082285,0,NULL,NULL,0,NULL,NULL,0,NULL,0,NULL);

(parent of new share is now a group folder - but problem issn't related to this, I switched to group folders last week to reduce the number of active shares)

Is there any process checking/killing/cleaning database entries at restart and is there any log what could get a glue why it's getting deleted?

[skjnldsv]

Could be a cron job just firing on boot

[tcg71]

After some testing: all oc_share entries with parent=0 were deleted on restart.

The question seems to be why a newly added user to a share got this value: already existing users of the same share (added on the same way [as users - not using a group] some time earlier) have parent=NULL.
Changing parent value on newly added user from 0 to NULL (no parent share) before restarting nextcloud keeps this share entry existing after restart.

So why are new share entries get parent=0 instead of NULL or parent share id?

[tcg71]

So why are new share entries get parent=0 instead of NULL or parent share id?

Ok, that was simple. Comparing table definition of oc_share with a second NC installation (on my Raspberry 4B) shows the difference. The default value for "parent" and "file_source" was different between them (both on same Ubuntu Snap and both without touching this database directly ever before). Setting default values of "parent" (and "file_source") from 0 to NULL solved my problem.

I wonder if this change is related to a restore operation of calendar and contact items using NextBackup a few month ago. It was the only database operation outside of regular NextCloud usage. So this issue may be a NextBackup-related issue.

Thank You @skjnldsv for Your help !