"Cannot access a closed file" is still a problem

stenp · September 9, 2026, 7:04am

I have the latest version of Duplicati running on my Win11. According to posts on this forum this error should have been fixed in previous version but it is still a problem.

Backup is made to Jottacloud and Secondary backup destination is SSH to a linux machine on my network.

It does not affect every file. Of the 34464 files only 284 gets this error.

Is there any setting of configuration I have to change to make this work?

kenkendk · September 10, 2026, 6:46am

Not sure what “Cannot access a closed file” refers to?
Did you mean “open file” ?

If so, the only way to solve this on Windows is to run Duplicati with elevated privileges so it can make a VSS snapshot and read locked files from there. An alternative is to use “backup-read”, but that also requires elevated privileges.

ts678 · September 10, 2026, 2:44pm

Guessing from Google search. Might be that fix for this didn’t fully fix it:

github.com/duplicati/duplicati

Bugfix/remote synchronization module fixes (#6809)

master ← carljohnsen:bugfix/remote-synchronization-module-fixes

opened 03:15PM - 18 Mar 26 UTC

carljohnsen

+1916 -1519

This PR addresses [this forum post](https://forum.duplicati.com/t/issues-with-mu…ltiple-backup-destinations-feature/22090/1) and #6806 . Specifically: - Remote synchronization has been added as a phase, which is shown in the UI progress. - Logging has been fixed so that logging (or printing) a remote synchronization config doesn't emit any secrets, such as auth id. - The "Cannot access a closed file" has been handled by moving the hash computation to before the put operation as this could (for some backends) close the file. - Errors and warnings produced during the remote synchronization phase has been added to the results, so the log and results are aligned again.

The “Cannot access a closed file” has been handled by moving the hash computation to before the put operation as this could (for some backends) close the file.

github.com/duplicati/duplicati

Error "Cannot access a closed file" when using multiple destinations

opened 07:29PM - 15 Mar 26 UTC

closed 06:56AM - 30 Apr 26 UTC

Bruceforce

- [x] I have searched open and closed issues for duplicates. - [x] I have se…arched the [forum](https://forum.duplicati.com) for related topics. --- ## Environment info - **Duplicati version**: 2.2.1.0 - 2.2.1.0_beta_2026-03-05 - **Operating system**: Docker Container on Debian - **Backend**: box.com with sync to pcloud ## Description I tried the new "multiple destinations" feature, where the primary destination is box.com/onedrive and the secondary is pcloud. In the live logs I get an `Error copying duplicati-b6dcff9e26e7a4ee2be0d848829d54deb.dblock.zip.aes: Cannot access a closed file.` for each file. Before the beta I did the sync "manually" using an rsync cronjob from box.com to pcloud which worked flawlessly. (related to #234). I also noticed that according to the pcloud UI it's stuck at exactly 1750 files uploaded since several hours, despite new files are added. Previously (before duplicati introduced the multi-destination feature I did the same using rclone, which worked flawlessly. For the same backup that was done by rclone, the pcloud UI lists 1807 files. Also the duplicati UI says "Backup complete!", which is weird, because according to the logs it still tries to upload all these files to pcloud. ## Steps to reproduce 1. Create a new backup with box.com as the first and pcloud (eu servers) as the second location 2. Start the backup 3. View live logs. - **Actual result**: `Error copying duplicati-b6dcff9e26e7a4ee2be0d848829d54deb.dblock.zip.aes: Cannot access a closed file.` for every file being processed - **Expected result**: No errors. ## Screenshots <img width="2214" height="1120" alt="Image" src="https://github.com/user-attachments/assets/a9b1d085-5668-4f93-a99f-2916ba4d0de9" /> Error in duplicati <img width="2238" height="816" alt="Image" src="https://github.com/user-attachments/assets/f6f551ce-9699-45b2-a0bf-939a0a89e6c7" /> but file uploaded to pcloud still <img width="2293" height="311" alt="Image" src="https://github.com/user-attachments/assets/f4d28a99-f48e-45e9-9999-2202df48ebaf" /> ## Debug log ``` Copying duplicati-b6d72cb6e066a49d79a942a1a40dc72b4.dblock.zip.aes from Box.com to pCloud (Native API) System.ObjectDisposedException: Cannot access a closed file. at RemoteSynchronization.RemoteSynchronizationRunner.CopyAsync(LightWeightBackendManager b_src, LightWeightBackendManager b_dst, IEnumerable`1 files, Config config, CancellationToken token) Error copying duplicati-b6dcff9e26e7a4ee2be0d848829d54deb.dblock.zip.aes: Cannot access a closed file. ... ```

Before assuming problem still exists, @stenp should verify message.

kenkendk · September 10, 2026, 2:47pm

Thanks! That makes a bit more sense then.

@stenp If this is indeed a multi-destination issue, please let us know which destinations you are using so we can reproduce it.

ts678 · September 10, 2026, 2:53pm

Original post has destination info, but we probably should specifically request confirmation that this was closed file (not open file) message.

stenp · September 10, 2026, 3:19pm

The error message is “Cannot access a closed file”. Everything I can find points to the same issue as #6809.

Primary destination is Jottacloud.

Secondary destination is ssh to a raspberry pi on my home network.

I have no problem with any of the two configurations if I set them up as single backup destination with no secondary destination.

stenp · September 10, 2026, 7:05pm

Here are some fresh errors from the log, seems like it is a sequence of 4 messages. I don’t know if this makes the backup invalid. This is the first of 556 errors in a backup of ca 84000 files.

2026-09-09 06:20:50 +02 - [Error-Duplicati.Library.Main.Backend.LightWeightBackendManager-rsync]: Error during operation: Get duplicati-b00b9b3c1ae9540c48b3d8c38fa0be551.dblock.zip
InvalidOperationException: Stream position mismatch after download for duplicati-b00b9b3c1ae9540c48b3d8c38fa0be551.dblock.zip

2026-09-09 06:20:52 +02 - [Error-Duplicati.Library.Main.Backend.LightWeightBackendManager-rsync]: Error during operation: Get duplicati-b00b9b3c1ae9540c48b3d8c38fa0be551.dblock.zip
ObjectDisposedException: Cannot access a closed file.

2026-09-09 06:20:54 +02 - [Error-Duplicati.Library.Main.Backend.LightWeightBackendManager-rsync]: Error during operation: Get duplicati-b00b9b3c1ae9540c48b3d8c38fa0be551.dblock.zip
ObjectDisposedException: Cannot access a closed file.

2026-09-09 06:20:55 +02 - [Error-Duplicati.Library.Main.Operation.RemoteSynchronization.RemoteSynchronizationRunner-CopyError]: Error copying duplicati-b00b9b3c1ae9540c48b3d8c38fa0be551.dblock.zip: Operation ‘Get duplicati-b00b9b3c1ae9540c48b3d8c38fa0be551.dblock.zip’ failed after 3 attempts.
InvalidOperationException: Operation ‘Get duplicati-b00b9b3c1ae9540c48b3d8c38fa0be551.dblock.zip’ failed after 3 attempts.