Windows 11 Explorer and other Apps (Word, Firefox ...) freez with NextCloud Client 33.0.x (up to 33.0.5)

[ACAPax]

⚠️ Before submitting, please verify the following: ⚠️

• This is a bug, not a question or a configuration issue.
• This issue is not already reported on Github (I have searched for it).
• Nextcloud Server and Desktop Client are up to date. See Server Maintenance and Release Schedule and Desktop Releases for supported versions.
• I agree to follow Nextcloud's Code of Conduct

Bug description

Just a quick note: There are one or two posts here describing similar issues.
#10123 (in this case, the client also loses its connection to the server during synchronization, whereas in my case, the Apps simply freezes without NextCloudClient losing the connection to the server)
However, since the symptoms differ slightly, we were advised on the NextCloud forum to create separate bug reports and let the developers decide whether they are related to the same issue.

Bug description
On Windows 11, when using VFS with very large NextCloud user directories, the NextCloud Client 33.0.x causes Explorer or other programs that are currently performing write operations on the file system to freeze (in my case, for 30–40 seconds).

I tested all client versions from 33.0.2 to 33.0.5 for several days each. The freezes disappeared immediately every time after downgrading to client 4.0.8 again.

Not every save operation is affected. For example, if I save 10 files one after another from Firefox to the NextCloud directory structure, the first 2 or 3 work without any problems, the fourth freezes, and then a few more work until the next freeze.

Steps to reproduce

1. Need a big nextcloud folder (My NexCloud Folder Explorer Information Size: 860 GB; Size on disk: 425 GB; Contents: 360,000 files, 12,000 folders)
2. Interact with the filesystem in the nexcloud folder (move single files, save files) 10 to 20 times in a row with individual files

Expected behavior

Regardless of whether the NexCloud client has started a SyncRun, the programs should continue to run without freezing

Which files are affected by this bug

All files

Operating system

Windows

Which version of the operating system you are running.

Windows 11

Installation method

Official Windows MSI

Nextcloud Server version

33.0.5

Nextcloud Desktop Client version

33.0.5

Did this occur after an update or on a clean installation?

Major version update (i.e. 4.0.0 → 33.0.0)

Are you using the Nextcloud Server Encryption module?

No

Are you using an external user-backend?

• Default internal user-backend
• LDAP or Active Directory
• SSO - SAML
• Other

Nextcloud Server logs

No relevant server log entries.

Additional info

Unfortunately, there are no clear entries in the logs (client and server) that indicate the error. However, since the error disappears immediately every time I downgrade to Client 4.0.8, I take this as an indication that the problem lies in the changes made between Client 4.0.8 and 33.0.x.

It is also notable that the freezes end at the exact same moment (to the nearest second, as far as can be determined by the Windows system clock) when the log shows “SyncEngine finished without problem. ... "Success"” and log rotation occurs.

[bigretromike]

Oh so its not only me ?

This is very clearly seen while using Visual Studio Code - unable to explore files, unable to run anything, only spinning icon

For unknown reason if I put laptop into sleep (but not always ? maybe timeout?) and go back to work the client looks like its working but no application (explorer, vsc) can access any (even those "local") files (im using vfs on windows).

The only reliable solution I found for this issue is to restart client (or reboot machine).

[ACAPax]

To help the developers identify the issues, I think it’s important to pinpoint exactly what the similarities and differences are.

Do you also have a large NextCloud folder (in terms of size and number of files)?
Are you running Windows 11 with VFS?
Did the problems start after updating to Client 33.0.x?
...

Based on our NextCloud User forum discussion (https://help.nextcloud.com/t/windows-11-explorer-freez-with-nextcloud-client-33-0-x-up-to-33-0-5/243345/19), it currently appears that NextCloud Client 33.0.x causes an issue on Windows 11 when dealing with a large index.

[bigretromike]

Do you also have a large NextCloud folder (in terms of size and number of files)?

YES ! (whole VFS contenct is around 400GB with many-many files and subfolders.

Are you running Windows 11 with VFS?

YES

Did the problems start after updating to Client 33.0.x? ...

No, this issue was known before probably around 3.x.x when ghost folders would appear, but was fixed? (regresion ?)

[bigretromike]

Best thing would be including debug logs when client re-creates those foldes (chech which one do it) because I had to fix the issue as soon as possible if you know what I mean.

For some reason some clients confuse synch data and things that something that is outdates is the latest synch configuration. From my observation with the issue its looks like the client database with syncstate is corrupted/outdated and there is not (or its not working) method to sync that/fix that with current server-sync-state. Because most of the clients is aware of "old folders" being already delete - and only few if any is not aware.

Server confuse those clients state with "new" folders being created;
And again - if folders are deleted from server using webui - all other clients see it and commit, and those with "corrupted" sync-state-database ignore it and force creating those folders.

I had similar issue with files but that one was ACL issue because files marked as "cloud" don't act the same way as those that are not-cloud (vfs), but I did not have any issues with deleting those folder on "corrupted" clients like I did with those with ACL issue.