nextcloud
[Bug]: Stuck "Couldn't convert to placeholder" sync error, even if file got synced properly
⚠️ 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
The desktop client constantly reports that a file could not be synced. While syncing, I can briefly see there error "Couldn't convert to placeholder". The message disappears once the sync is finished.
This is not the first time the bug has happened. I managed to work around it by renaming the file to something else and then back to its original name. It did not work this time around...
It's worth noting that the file gets properly synced. It's just a very annoying error message. I can see the file on nextcloud web, download it and read it fine.
There are multiple reports of this problem on github, all closed.
Steps to reproduce
Happens quite randomly, I have no idea how to reproduce the issue. What I can say is that I'm using virtual file sync and that the file is in a nextcloud group folder.
Expected behavior
Syncing is marked has finished. Also, it would be nice if the error stayed displayed and above all other messages so that it is easier to understand that there is a problem.
Which files are affected by this bug
A wav file, but it already happened multiple times with different types of files (images, videos...)
Operating system
Windows
Which version of the operating system you are running.
Windows 11
Package
Official Windows MSI
Nextcloud Server version
32.0.1
Nextcloud Desktop Client version
4.0.1
Is this bug present after an update or on a fresh install?
Updated from a minor version (ex. 3.16.1 to 3.16.2)
Are you using the Nextcloud Server Encryption module?
Encryption is Disabled
Are you using an external user-backend?
- [x] Default internal user-backend
- [ ] LDAP/ Active Directory
- [ ] SSO - SAML
- [ ] Other
Nextcloud Server logs
Nothing much happens server side, just a bunch of PROPFIND. Logical since there is nothing to sync.
Additional info
This happens regularly for me as well. I sync my Desktop/Documents/Pictures folders in Windows 11 and use the virtual files which I assume is the root of this issue. It happens EVERY time I take a screenshot with the snipping tool I can reproduce 100% of the time if anyone needs more logs or anything. But also randomly as the OP stated other files will error out, like I saved some STL files to my desktop this morning and landed on the same error, renaming, or moving it to another folder then back, usually fixes it for whatever reason but it's frustrating.
I finally found a workaround for this particular file. No matter what, (renaming, moving, whatever) it wouldn't "sync" (although the file is actually synced, it's just the UI that says it's not). To workaround the bug this time, I removed the file from the virtual drive and then uploaded it through the web UI. It got synced back to the computer properly. Quite annoying.
I finally found a workaround for this particular file. No matter what, (renaming, moving, whatever) it wouldn't "sync" (although the file is actually synced, it's just the UI that says it's not). To workaround the bug this time, I removed the file from the virtual drive and then uploaded it through the web UI. It got synced back to the computer properly. Quite annoying.
I really wish this issue would get resolved overall, or if nothing else I could figure out the root cause. I disabled syncing of my snapshot folder because EVERY snapshot would error out. Copying the file manually isn't a long term workaround imo.
I think the root cause here is actually Windows handling of multiple cloud providers in the same folder.
If the affected file is inside a directory that’s also synced by OneDrive (for example Desktop/Documents/Pictures on Windows 11), OneDrive is already using Windows’ Files-On-Demand system. When Nextcloud tries to convert the same file into a VFS placeholder, Windows rejects it because the file is already “owned” by another sync provider.
That leads to the persistent:
Couldn't convert to placeholder
even though the file itself syncs correctly.
Moving the file to a folder outside the OneDrive-controlled paths (e.g. C:\NextcloudTest) instantly stops the issue. Renaming/moving sometimes “fixes” it because it temporarily releases OneDrive’s placeholder lock.
So the behavior isn’t random, it's just two VFS systems fighting over the same file. The solution is to avoid syncing Nextcloud VFS inside OneDrive-managed folders.
@borkedporcupine You mentioned using a local path under Desktop/Documents/Pictures. On many Windows setups those folders are synced by OneDrive by default, so my guess is that OneDrive or another provider is active on your Documents/Desktop and causing the conflict.
I don't have OneDrive and my Nextcloud sync is in c:\Users\Daniel\Nextcloud, outside of the c:\Users\Daniel\OneDrive folder that windows creates anyway... So I don't think this is related to the issue I raised.