[Bug]: Nextcloud not responding which also causes File Explorer/ALL file access on Windows to freeze

[munrobasher]

⚠️ Before submitting, please verify the following: ⚠️

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

Bug description

Nextcloud client is not responding and causes entire local Windows file system to freeze/not respond. This is a HIGHLY disruptive problem - priority #1 in the helpdesk. First symptom is not been able to open any files that aren't already downloaded. They get the "Downloading 1 item" window but it sticks at 100%.

Steps to reproduce

1. Kill nextcloud.exe process from task manager or stop-process nextcloud
2. Open Nextcloud client
3. Icon goes green for a second and then switches to synchronising status
4. Clicking on the Nextcloud client icon doesn't do anything - can't right-click either
5. Try and open File Explorer and it freezes
6. Run that stop-process again and File Explorer immediately opens. Nextcloud is clearly blocking File Explorer

Expected behavior

Nextcloud should synchronise and download files normally. It should not cause File Explorer to freeze.

Which files are affected by this bug

All files

Operating system

Windows

Which version of the operating system you are running.

Windows 11

Package

Appimage

Nextcloud Server version

28.0.2

Nextcloud Desktop Client version

3.11.1

Is this bug present after an update or on a fresh install?

Fresh desktop client install

Are you using the Nextcloud Server Encryption module?

Encryption is Enabled

Are you using an external user-backend?

• [ ] Default internal user-backend
• [ ] LDAP/ Active Directory
• [ ] SSO - SAML
• [ ] Other

Nextcloud Server logs

Too many logs to include here. Can be downloaded from my OneDrive:

https://maltsystems-my.sharepoint.com/:u:/g/personal/rob_nicholson_maltsystems_co_uk/ESTfwyRlcHxHrdIPFteeOQ8BTYuW4b_oZiyFBhmNkpJ8rA?e=Chrbbw

Additional info

My client is rightly pulling their hair out as they can't work effectively. The problem has effected the entire company.

I had to work this evening to try and fix the finance director's installation. I managed to get access to their laptop for an hour. I was only able to fix it by remove their entry from [account] in config and logging them in again using the same folder.

This sort of worked except the client kept reporting this notification every few seconds: https://i.imgur.com/w5xl78X.png

This rang alarm bells as I'd been doing some work in that folder this morning. This is a bit of a vague memory but what I did was this:

1. Unzipped a large printer driver into the same folder as the zip file
2. Nextcloud on my PC will have started to upload the unzip file
3. I immediately re-zipped the folder using 7-Zip with delete option set
4. This will have deleted the unzipped files most likely before Nextcloud had finished uploading them

A key bit of information here - this is in a group folder that's read-only to most users (it's a library folder). I have write access.

When I looked in the local Nextcloud folder on the laptop above, there was part of the unzipped folder present. Here is the above with some screenshots

1. The original folder looked like this: https://i.imgur.com/CtMIzAs.png - it will have been like this for a long time.
2. I unzipped the file to this: https://i.imgur.com/GnZpSbl.png
3. Immediately zipped up the folder again with delete option set in 7-zip

Some screenshots:

[munrobasher]

This was what happened when I killed nextcloud.exe, removed (or rather renamed) the [accounts] section in config, re-launched Nextcloud and logged on again, using same folder:

The interesting bit here is about getting cleared. All this synchronisation is happening in a folder that is read-only for the users. They shouldn't be able to even add files to that folder. I'm going to do some further tests on read-only group folders as I my gut instinct is that's where the issue is stemming from.

[munrobasher]

I'm trying to repeat this in the lab on my own Nextcloud installation. I've managed to crash Nextclient client. All I was doing was using robocopy to copy a large folder (containing software) into a group folder.

There was a notification about not being able to sync a file which wasn't unexpected as robocopy was probably still copying it. But now I've got a red X on Nextcloud and I can't interact with the client. The Nextcloud process is using 0% CPU:

[munrobasher]

I stopped the crashed Nextcloud instance and restarted it - at which point it's started uploading the new copies files:

Here are the logs after restarting Nextcloud. NOTE: this on different platform and not exactly the same situation as the subject line but it's associated with trying to repeat it.

Nextcloud logs (red cross on Fangorn).zip

[munrobasher]

More logs from another user with same problem: Nextcloud client not responding and File Explorer won't open. My fix at the moment is to kill the process, manually delete some recently deleted folders in the read-only library, rename [accounts] as [accounts.bak] in config, restart Nextcloud.

Two sets of logs. Firstly the logs as I found them on the problematic computer. Second set after I enabled logDebug=true.

Nextcloud logs (Chris before debug).zip Nextcloud logs (Chris with debug).zip

[mocmichal]

same here, icon not responding, blocking windows explorer and total commander RMB menu. Win10, Nextcloud 3.12.1 (2024-03-06).

[mikemayuare]

This is happening to me with fedroa 39, three different clients 3.12 .1 version, unofficial flatpak, official AppImage and distribution package, is not a package problem but upstream. It freezes after reaching certain file(s) that are not logged and cannot spot which those are. Errors are not logged.