Target File Size is Different from the Source Length

St_Paul · June 11, 2025, 4:53pm

I am running a backup for a nonprofit church to backup important knowledge, pictures, files, etc. to a Google Drive and two other accounts so that in case of data lose, we can have more than one option to restore the information. It’s been working really well, pretty much set on autopilot and let it run each night, until recently. Now I keep receiving this error message, but only on the Google Drive account:

One or more errors occurred. (Target file size (51,970,048) is different from the source length (52,365,149). Target: H:\My Drive\Backup\duplicati-b48b66ff5dc0c431ca8d7a3736e5b51e8.dblock.zip.aes (Target file size (51,970,048) is different from the source length (52,365,149). Target: H:\My Drive\Backup\duplicati-b48b66ff5dc0c431ca8d7a3736e5b51e8.dblock.zip.aes) (One or more errors occurred. (Target file size (51,970,048) is different from the source length (52,365,149). Target: H:\My Drive\Backup\duplicati-b48b66ff5dc0c431ca8d7a3736e5b51e8.dblock.zip.aes)))

I have attempted to export the configuration file, delete the old configuration, deleted all files on the Google Drive and emptied the recycle bin, and restore the file. Same error message.
I have attempted to completely delete the configuration file, deleted all files on the Google Drive and emptied the recycle bin, and created a completely new configuration. Same error message.
–A) Also, attempted to remove source data ‘My Documents’ and tried a much smaller 3GB worth of ‘My Pictures’ to see if the data size may be causing issues. We are nowhere near our storage capacity limit.

Any suggestions would help as I would like to get their backup option up and running again as soon as possible.

Thank you!

St_Paul · June 11, 2025, 5:32pm

Deleted per above and created a new and renamed configuration from scratch again. The same warning & errors occurs.

Additional Log Info:

Time
Start 2025-06-11 12:25:33
End 2025-06-11 12:26:59
Duration 00:01:26

Warnings 1:

2025-06-11 12:26:59 -05 - [Warning-Duplicati.Library.Main.Operation.Backup.BackendUploader-UploadError]: Error during upload failure: Target file size (65,536) is different from the source length (68,717). Target: H:\My Drive\Backup1\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes
FileMissingException: Target file size (65,536) is different from the source length (68,717). Target: H:\My Drive\Backup1\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes

Errors 2:

2025-06-11 12:26:59 -05 - [Error-Duplicati.Library.Main.Operation.BackupHandler-FatalError]: Fatal error
FileMissingException: Target file size (65,536) is different from the source length (68,717). Target: H:\My Drive\Backup1\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes

2025-06-11 12:26:59 -05 - [Error-Duplicati.Library.Main.Controller-FailedOperation]: The operation Backup has failed with error: One or more errors occurred. (Target file size (65,536) is different from the source length (68,717). Target: H:\My Drive\Backup1\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes (Target file size (65,536) is different from the source length (68,717). Target: H:\My Drive\Backup1\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes) (One or more errors occurred. (Target file size (65,536) is different from the source length (68,717). Target: H:\My Drive\Backup1\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes)))
AggregateException: One or more errors occurred. (Target file size (65,536) is different from the source length (68,717). Target: H:\My Drive\Backup1\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes (Target file size (65,536) is different from the source length (68,717). Target: H:\My Drive\Backup1\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes) (One or more errors occurred. (Target file size (65,536) is different from the source length (68,717). Target: H:\My Drive\Backup1\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes)))

Complete Log:

            {
  "DeletedFiles": 0,
  "DeletedFolders": 0,
  "ModifiedFiles": 0,
  "ExaminedFiles": 7316,
  "OpenedFiles": 7314,
  "AddedFiles": 7314,
  "SizeOfModifiedFiles": 0,
  "SizeOfAddedFiles": 1994220826,
  "SizeOfExaminedFiles": 2081723230,
  "SizeOfOpenedFiles": 1994220826,
  "NotProcessedFiles": 0,
  "AddedFolders": 820,
  "TooLargeFiles": 0,
  "FilesWithError": 0,
  "ModifiedFolders": 0,
  "ModifiedSymlinks": 0,
  "AddedSymlinks": 3,
  "DeletedSymlinks": 0,
  "PartialBackup": false,
  "Dryrun": false,
  "MainOperation": "Backup",
  "CompactResults": null,
  "VacuumResults": null,
  "DeleteResults": null,
  "RepairResults": null,
  "TestResults": null,
  "ParsedResult": "Fatal",
  "Interrupted": false,
  "Version": "2.1.0.5 (2.1.0.5_stable_2025-03-04)",
  "EndTime": "2025-06-11T17:26:59.5658212Z",
  "BeginTime": "2025-06-11T17:25:33.2158365Z",
  "Duration": "00:01:26.3499847",
  "MessagesActualLength": 122,
  "WarningsActualLength": 1,
  "ErrorsActualLength": 2,
  "Messages": [
    "2025-06-11 12:25:33 -05 - [Information-Duplicati.Library.Main.Controller-StartingOperation]: The operation Backup has started",
    "2025-06-11 12:25:33 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: List - Started:  ()",
    "2025-06-11 12:25:33 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: List - Completed:  ()",
    "2025-06-11 12:26:06 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-b0b1bfa4e284b42a593f444bf6d3fe214.dblock.zip.aes (49.23 MB)",
    "2025-06-11 12:26:06 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-bc2c39b8015e240f188684f20969deb9c.dblock.zip.aes (49.97 MB)",
    "2025-06-11 12:26:06 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-b5d9ee41cb21842bea90dd784a7b51777.dblock.zip.aes (49.52 MB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-b0b1bfa4e284b42a593f444bf6d3fe214.dblock.zip.aes (49.23 MB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-bc2c39b8015e240f188684f20969deb9c.dblock.zip.aes (49.97 MB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-bd938e0714d4448c59eb624e2622b4728.dblock.zip.aes (49.15 MB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-b5d9ee41cb21842bea90dd784a7b51777.dblock.zip.aes (49.52 MB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-iee028df6b326447a8885d4dac336e540.dindex.zip.aes (60.31 KB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-iee028df6b326447a8885d4dac336e540.dindex.zip.aes (60.31 KB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-ie367aa76d08d46d4bfea618b106c00e1.dindex.zip.aes (67.11 KB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-b739af66c08f54759909767df4ac7a94b.dblock.zip.aes (49.67 MB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-if774370217d847f7a3e9d64106ff67b6.dindex.zip.aes (56.39 KB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-if774370217d847f7a3e9d64106ff67b6.dindex.zip.aes (56.39 KB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Retrying: duplicati-ie367aa76d08d46d4bfea618b106c00e1.dindex.zip.aes (67.11 KB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Completed: duplicati-bd938e0714d4448c59eb624e2622b4728.dblock.zip.aes (49.15 MB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Retrying: duplicati-b739af66c08f54759909767df4ac7a94b.dblock.zip.aes (49.67 MB)",
    "2025-06-11 12:26:07 -05 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: Put - Started: duplicati-i508d0688ebeb44219fb70a2f0bcf88a3.dindex.zip.aes (57.84 KB)"
  ],
  "Warnings": [
    "2025-06-11 12:26:59 -05 - [Warning-Duplicati.Library.Main.Operation.Backup.BackendUploader-UploadError]: Error during upload failure: Target file size (65,536) is different from the source length (68,717). Target: H:\\My Drive\\Backup1\\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes\r\nFileMissingException: Target file size (65,536) is different from the source length (68,717). Target: H:\\My Drive\\Backup1\\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes"
  ],
  "Errors": [
    "2025-06-11 12:26:59 -05 - [Error-Duplicati.Library.Main.Operation.BackupHandler-FatalError]: Fatal error\r\nFileMissingException: Target file size (65,536) is different from the source length (68,717). Target: H:\\My Drive\\Backup1\\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes",
    "2025-06-11 12:26:59 -05 - [Error-Duplicati.Library.Main.Controller-FailedOperation]: The operation Backup has failed with error: One or more errors occurred. (Target file size (65,536) is different from the source length (68,717). Target: H:\\My Drive\\Backup1\\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes (Target file size (65,536) is different from the source length (68,717). Target: H:\\My Drive\\Backup1\\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes) (One or more errors occurred. (Target file size (65,536) is different from the source length (68,717). Target: H:\\My Drive\\Backup1\\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes)))\r\nAggregateException: One or more errors occurred. (Target file size (65,536) is different from the source length (68,717). Target: H:\\My Drive\\Backup1\\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes (Target file size (65,536) is different from the source length (68,717). Target: H:\\My Drive\\Backup1\\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes) (One or more errors occurred. (Target file size (65,536) is different from the source length (68,717). Target: H:\\My Drive\\Backup1\\duplicati-i627246ebcbc04620b1d70f75a4bd94aa.dindex.zip.aes)))"
  ],
  "BackendStatistics": {
    "RemoteCalls": 35,
    "BytesUploaded": 363271529,
    "BytesDownloaded": 0,
    "FilesUploaded": 13,
    "FilesDownloaded": 0,
    "FilesDeleted": 0,
    "FoldersCreated": 0,
    "RetryAttempts": 20,
    "UnknownFileSize": 0,
    "UnknownFileCount": 0,
    "KnownFileCount": 0,
    "KnownFileSize": 0,
    "LastBackupDate": "0001-01-01T00:00:00",
    "BackupListCount": 0,
    "TotalQuotaSpace": 509244076032,
    "FreeQuotaSpace": 229929443328,
    "AssignedQuotaSpace": -1,
    "ReportedQuotaError": false,
    "ReportedQuotaWarning": false,
    "MainOperation": "Backup",
    "ParsedResult": "Success",
    "Interrupted": false,
    "Version": "2.1.0.5 (2.1.0.5_stable_2025-03-04)",
    "EndTime": "0001-01-01T00:00:00",
    "BeginTime": "2025-06-11T17:25:33.2158408Z",
    "Duration": "00:00:00",
    "MessagesActualLength": 0,
    "WarningsActualLength": 0,
    "ErrorsActualLength": 0,
    "Messages": null,
    "Warnings": null,
    "Errors": null
  }
}

ts678 · June 11, 2025, 6:11pm

Welcome to the forum @St_Paul

Did anything change recently that might be related?

It seems like Google Drive changed its behavior, assuming nothing else changed.

Generally it’s a worse plan to write Google Drive letters, as Duplicati lacks control.

Stream & mirror files with Drive for desktop shows ways to set up drive’s behavior.
Are you using “Stream files” or “Mirror files”?

Whatever it is is telling Duplicati that the new file is smaller than the file size written.
As seems common in some of these errors, the reported sizes are very binary-even.

51970048 is 0x3190000
65536 is 0x10000

Maybe this is a temporary problem that will get fixed by Google Drive after file upload.
This is main lack of control for Duplicati, especially for mirroring. File can upload later.
This leaves you believing all is done, but it’s not. Streaming is probably better on that.
Google Drive Destination is the best, as Duplicati doesn’t use a drive, but goes direct.
There are other issues with Google Drive, and there is a currently discussion in forum.

I suggest you look with Explorer or something, for any file that has “wrong” target size.
Maybe it eventually gets right. If so, and you really want to keep using drive letter with
File Destination, Disabling length verification says how to stop Duplicati from checking immediately after the file write. You’ll still have some checking at the end of the backup.

St_Paul · June 11, 2025, 7:21pm

Thanks for the warm welcome and assistance.

Nothing that is obvious to me.

I agree. Was hoping that it was not a Google side issue.

Stream files.

This is the solution! Thank you! I was able to complete a full backup with the source directly being Google Drive, bypassing the original method that no longer works correctly. Then made a change to the time, had to re-enter the source, and did another run and it continued to work.

tl;dr

I was trying to go Google Drive direct without streaming using the Windows drive letter and your Google Drive Destination link provided the solution! I was attempting to set the Backup destination >> Storage Type >> Google Drive, but could not find the correct link format. Your link provided that as googledrive://<folder>/<subfolder>?authid=<authid>. The authid can be generated in Duplicati (or externally, but it provides the link). I had to try creating a folder a few times withing Google Drive, and then realized Duplicati could create a folder too. The documentation doesn’t fully explain that it literally creates a \googledrive\~\Backup subfolder on Google Drive, but that is fine. It’s probably doing some Linux root filesystem from the looks of it.

Two strange things- I added the source as googledrive://Backup/ and also the authid is not added to the end, instead it is added in the field below, which makes sense in Duplicati, but does not make sense in the documentation.

Hopefully this conversation will help some other individual who may be experiencing the same or a similar issue.

ts678 · June 11, 2025, 7:43pm

What sort of Google Drive account is this? My personal account just makes ~\folder.

is where Backup subfolder is from, but is it in root in Google web UI, or buried deeper?
Note that the URL form is for a command line. In the web UI, the fields are broken out:

AFAIK, the Destination path is just the desired path or file from root. No googledrive.

If you want GUI to show you the put-together URL, you can request to look at that with

I’m also assuming that many “source” references in your last post refer to “destination”.

Before switching plan, did you check “bad” file lengths in Explorer or Google’s web UI?
It would be interesting to know if the file lengths eventually went up to the correct value.

St_Paul · June 11, 2025, 8:07pm

It is a Google Drive account. It looks the same as a personal account, but it was created for a nonprofit church & school, so there may be some differences.

You are correct. That would make more sense. In retrospect, I should have just entered ‘Backup’ in the Destination path, but since I already set it up, I think I will leave it as is though, since it won’t harm anything. Good to know about the GUI for future reference.

Correct. I’m probably using the wrong terminology as I don’t really have any tech training. Apologies for any confusion.

TBH, I wasn’t exactly sure how to do so. I was originally hoping that by recreating the configuration it would have solved the issue. If it would be useful to you or the devs, I could create the old config, let it fail, and post the results. Just let me know what to do.

ts678 · June 11, 2025, 8:28pm

Probably that can be left to the next person if they insist on sticking with drive letter plan, then if it looks promising they can try the --disable-length-verification workaround.

The current problem with the Google Drive destination FWIW is that Google occasionally seems to forget that Duplicati made the files, so won’t give it access. Cause is unknown.

St_Paul · June 12, 2025, 1:34pm

Good to know. If anyone needs more info from me, they can always reach out here and let me know what they need. Duplicati is a great product.

I miss the days when Google’s motto / code of conduct was “Don’t be evil.” That being said, this issue may just be off their radar due to this being another party’s product, separate from their business model.