Backup error with CryptographicException

Support
1

Hi folks,

I’m getting the following warnings and errors on my backup:

1. 2025-08-27 09:03:08 +02 - \[Error-Duplicati.Library.Main.Operation.TestHandler-FailedToProcessFile\]: Failed to process file duplicati-i7aac0c7aaab94e8099ee752393504181.dindex.zip.aes CryptographicException: Failed to read 5 bytes, likely not an encrypted archive
2. 2025-08-27 09:03:50 +02 - \[Error-Duplicati.Library.Main.Operation.TestHandler-FailedToProcessFile\]: Failed to process file duplicati-i391fe28b10b247909be768dfc9e998a1.dindex.zip.aes CryptographicException: Failed to read 5 bytes, likely not an encrypted archive
3. 2025-08-27 09:04:31 +02 - \[Error-Duplicati.Library.Main.Operation.TestHandler-FailedToProcessFile\]: Failed to process file duplicati-i5a42c84e76d0433698c3b5ceb9102b1b.dindex.zip.aes CryptographicException: Failed to read 5 bytes, likely not an encrypted archive
4. 2025-08-27 09:04:37 +02 - \[Error-Duplicati.Library.Main.Operation.TestHandler-Test results\]: Verified 18 remote files with 3 problem(s)

The complete log reads like this:

{
“DeletedFiles”: 1,
“DeletedFolders”: 0,
“ModifiedFiles”: 26,
“ExaminedFiles”: 142349,
“OpenedFiles”: 26,
“AddedFiles”: 0,
“SizeOfModifiedFiles”: 12604393,
“SizeOfAddedFiles”: 0,
“SizeOfExaminedFiles”: 290736297390,
“SizeOfOpenedFiles”: 12653557,
“NotProcessedFiles”: 0,
“AddedFolders”: 0,
“TooLargeFiles”: 0,
“FilesWithError”: 0,
“ModifiedFolders”: 0,
“ModifiedSymlinks”: 0,
“AddedSymlinks”: 0,
“DeletedSymlinks”: 0,
“PartialBackup”: false,
“Dryrun”: false,
“MainOperation”: “Backup”,
“CompactResults”: {
“DeletedFileCount”: 0,
“DownloadedFileCount”: 0,
“UploadedFileCount”: 0,
“DeletedFileSize”: 0,
“DownloadedFileSize”: 0,
“UploadedFileSize”: 0,
“Dryrun”: false,
“VacuumResults”: null,
“MainOperation”: “Compact”,
“ParsedResult”: “Success”,
“Interrupted”: false,
“Version”: “2.1.0.5 (2.1.0.5_stable_2025-03-04)”,
“EndTime”: “2025-08-27T07:07:48.777338Z”,
“BeginTime”: “2025-08-27T07:07:38.6207227Z”,
“Duration”: “00:00:10.1566153”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null,
“BackendStatistics”: {
“RemoteCalls”: 35,
“BytesUploaded”: 16946391,
“BytesDownloaded”: 606332563,
“FilesUploaded”: 3,
“FilesDownloaded”: 15,
“FilesDeleted”: 0,
“FoldersCreated”: 0,
“RetryAttempts”: 12,
“UnknownFileSize”: 0,
“UnknownFileCount”: 0,
“KnownFileCount”: 4958,
“KnownFileSize”: 257264525407,
“LastBackupDate”: “2025-08-27T09:07:05+02:00”,
“BackupListCount”: 11,
“TotalQuotaSpace”: 0,
“FreeQuotaSpace”: 0,
“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”: “2025-08-27T07:07:05.538142Z”,
“Duration”: “00:00:00”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null
}
},
“VacuumResults”: null,
“DeleteResults”: {
“DeletedSetsActualLength”: 0,
“DeletedSets”: [ ],
“Dryrun”: false,
“MainOperation”: “Delete”,
“CompactResults”: {
“DeletedFileCount”: 0,
“DownloadedFileCount”: 0,
“UploadedFileCount”: 0,
“DeletedFileSize”: 0,
“DownloadedFileSize”: 0,
“UploadedFileSize”: 0,
“Dryrun”: false,
“VacuumResults”: null,
“MainOperation”: “Compact”,
“ParsedResult”: “Success”,
“Interrupted”: false,
“Version”: “2.1.0.5 (2.1.0.5_stable_2025-03-04)”,
“EndTime”: “2025-08-27T07:07:48.777338Z”,
“BeginTime”: “2025-08-27T07:07:38.6207227Z”,
“Duration”: “00:00:10.1566153”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null,
“BackendStatistics”: {
“RemoteCalls”: 35,
“BytesUploaded”: 16946391,
“BytesDownloaded”: 606332563,
“FilesUploaded”: 3,
“FilesDownloaded”: 15,
“FilesDeleted”: 0,
“FoldersCreated”: 0,
“RetryAttempts”: 12,
“UnknownFileSize”: 0,
“UnknownFileCount”: 0,
“KnownFileCount”: 4958,
“KnownFileSize”: 257264525407,
“LastBackupDate”: “2025-08-27T09:07:05+02:00”,
“BackupListCount”: 11,
“TotalQuotaSpace”: 0,
“FreeQuotaSpace”: 0,
“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”: “2025-08-27T07:07:05.538142Z”,
“Duration”: “00:00:00”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null
}
},
“ParsedResult”: “Success”,
“Interrupted”: false,
“Version”: “2.1.0.5 (2.1.0.5_stable_2025-03-04)”,
“EndTime”: “2025-08-27T07:07:48.7773423Z”,
“BeginTime”: “2025-08-27T07:07:31.7696086Z”,
“Duration”: “00:00:17.0077337”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null,
“BackendStatistics”: {
“RemoteCalls”: 35,
“BytesUploaded”: 16946391,
“BytesDownloaded”: 606332563,
“FilesUploaded”: 3,
“FilesDownloaded”: 15,
“FilesDeleted”: 0,
“FoldersCreated”: 0,
“RetryAttempts”: 12,
“UnknownFileSize”: 0,
“UnknownFileCount”: 0,
“KnownFileCount”: 4958,
“KnownFileSize”: 257264525407,
“LastBackupDate”: “2025-08-27T09:07:05+02:00”,
“BackupListCount”: 11,
“TotalQuotaSpace”: 0,
“FreeQuotaSpace”: 0,
“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”: “2025-08-27T07:07:05.538142Z”,
“Duration”: “00:00:00”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null
}
},
“RepairResults”: null,
“TestResults”: {
“MainOperation”: “Test”,
“VerificationsActualLength”: 18,
“Verifications”: \[
{
“Key”: “duplicati-i7aac0c7aaab94e8099ee752393504181.dindex.zip.aes”,
“Value”: \[
{
“Key”: “Error”,
“Value”: “Failed to read 5 bytes, likely not an encrypted archive”
}
\]
},
{
“Key”: “duplicati-i391fe28b10b247909be768dfc9e998a1.dindex.zip.aes”,
“Value”: \[
{
“Key”: “Error”,
“Value”: “Failed to read 5 bytes, likely not an encrypted archive”
}
\]
},
{
“Key”: “duplicati-i5a42c84e76d0433698c3b5ceb9102b1b.dindex.zip.aes”,
“Value”: \[
{
“Key”: “Error”,
“Value”: “Failed to read 5 bytes, likely not an encrypted archive”
}
\]
},
{
“Key”: “duplicati-20250827T070705Z.dlist.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-20241022T125049Z.dlist.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-20241123T073156Z.dlist.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-20250822T092416Z.dlist.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-20250827T070126Z.dlist.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-i01818809cfb94568b5d1fb58fb925234.dindex.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-i11290d2ecf174cfb8f3327c5be58b58a.dindex.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-i62948b2bc02a464e913dc29f518fd787.dindex.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-id09f7aa078454aa0ab85c06350866ecb.dindex.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-ia57dbfe5876f4f04a5112ecb8bd24294.dindex.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-b794d366b3e59468c8a6926ff5db75563.dblock.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-bcd3e35c6686241b09ff61936e7852a15.dblock.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-b4d544a07619d4c4b8bc53c7a96484e68.dblock.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-be8ef9d9fc2b2444ba38a2e453504d194.dblock.zip.aes”,
“Value”: [ ]
},
{
“Key”: “duplicati-b45f8f2939e2d443a93eba4bfb4c43c72.dblock.zip.aes”,
“Value”: [ ]
}
\],
“ParsedResult”: “Success”,
“Interrupted”: false,
“Version”: “2.1.0.5 (2.1.0.5_stable_2025-03-04)”,
“EndTime”: “2025-08-27T07:09:59.8037829Z”,
“BeginTime”: “2025-08-27T07:07:49.1056237Z”,
“Duration”: “00:02:10.6981592”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null,
“BackendStatistics”: {
“RemoteCalls”: 35,
“BytesUploaded”: 16946391,
“BytesDownloaded”: 606332563,
“FilesUploaded”: 3,
“FilesDownloaded”: 15,
“FilesDeleted”: 0,
“FoldersCreated”: 0,
“RetryAttempts”: 12,
“UnknownFileSize”: 0,
“UnknownFileCount”: 0,
“KnownFileCount”: 4958,
“KnownFileSize”: 257264525407,
“LastBackupDate”: “2025-08-27T09:07:05+02:00”,
“BackupListCount”: 11,
“TotalQuotaSpace”: 0,
“FreeQuotaSpace”: 0,
“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”: “2025-08-27T07:07:05.538142Z”,
“Duration”: “00:00:00”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null
}
},
“ParsedResult”: “Error”,
“Interrupted”: false,
“Version”: “2.1.0.5 (2.1.0.5_stable_2025-03-04)”,
“EndTime”: “2025-08-27T07:09:59.8475704Z”,
“BeginTime”: “2025-08-27T07:07:05.5381398Z”,
“Duration”: “00:02:54.3094306”,
“MessagesActualLength”: 81,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 4,
“Messages”: \[
“2025-08-27 09:07:05 +02 - \[Information-Duplicati.Library.Main.Controller-StartingOperation\]: Die Operation Backup wurde gestartet”,
“2025-08-27 09:07:11 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: List - Started:  ()”,
“2025-08-27 09:07:11 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: List - Completed:  (4,84 KB)”,
“2025-08-27 09:07:28 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: Put - Started: duplicati-baada5300d3224c09bdd46a1461615d29.dblock.zip.aes (559,90 KB)”,
“2025-08-27 09:07:29 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: Put - Completed: duplicati-baada5300d3224c09bdd46a1461615d29.dblock.zip.aes (559,90 KB)”,
“2025-08-27 09:07:30 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: Put - Started: duplicati-i3fc5d7ff439e47c6a8f86cf58dbd7917.dindex.zip.aes (8,87 KB)”,
“2025-08-27 09:07:30 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: Put - Completed: duplicati-i3fc5d7ff439e47c6a8f86cf58dbd7917.dindex.zip.aes (8,87 KB)”,
“2025-08-27 09:07:31 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: Put - Started: duplicati-20250827T070705Z.dlist.zip.aes (15,61 MB)”,
“2025-08-27 09:07:31 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: Put - Completed: duplicati-20250827T070705Z.dlist.zip.aes (15,61 MB)”,
“2025-08-27 09:07:31 +02 - \[Information-Duplicati.Library.Main.Operation.DeleteHandler:RetentionPolicy-StartCheck\]: Start checking if backups can be removed”,
“2025-08-27 09:07:31 +02 - \[Information-Duplicati.Library.Main.Operation.DeleteHandler:RetentionPolicy-FramesAndIntervals\]: Time frames and intervals pairs: 7.00:00:00 / 1.00:00:00, 28.00:00:00 / 7.00:00:00, 365.00:00:00 / 31.00:00:00”,
“2025-08-27 09:07:31 +02 - \[Information-Duplicati.Library.Main.Operation.DeleteHandler:RetentionPolicy-BackupList\]: Backups to consider: 27.08.2025 09:01:26, 22.08.2025 12:09:22, 22.08.2025 11:24:16, 16.08.2025 16:03:36, 05.08.2025 09:50:32, 25.07.2025 08:08:51, 18.06.2025 08:22:53, 24.12.2024 15:12:49, 23.11.2024 08:31:56, 22.10.2024 14:50:49”,
"2025-08-27 09:07:31 +02 - \[Information-Duplicati.Library.Main.Operation.DeleteHandler:RetentionPolicy-BackupsToDelete\]: Backups outside of all time frames and thus getting deleted: ",
"2025-08-27 09:07:31 +02 - \[Information-Duplicati.Library.Main.Operation.DeleteHandler:RetentionPolicy-AllBackupsToDelete\]: All backups to delete: ",
“2025-08-27 09:07:38 +02 - \[Information-Duplicati.Library.Main.Operation.DeleteHandler-DeleteResults\]: No remote filesets were deleted”,
“2025-08-27 09:07:48 +02 - \[Information-Duplicati.Library.Main.Database.LocalDeleteDatabase-CompactReason\]: Compacting not required”,
“2025-08-27 09:07:48 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: List - Started:  ()”,
“2025-08-27 09:07:49 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: List - Completed:  (4,84 KB)”,
“2025-08-27 09:07:49 +02 - \[Information-Duplicati.Library.Main.Operation.TestHandler-MissingRemoteHash\]: No hash or size recorded for duplicati-i7aac0c7aaab94e8099ee752393504181.dindex.zip.aes, performing full verification”,
“2025-08-27 09:07:49 +02 - \[Information-Duplicati.Library.Main.BasicResults-BackendEvent\]: Backend event: Get - Started: duplicati-i7aac0c7aaab94e8099ee752393504181.dindex.zip.aes ()”
\],
“Warnings”: [ ],
“Errors”: \[
“2025-08-27 09:08:30 +02 - \[Error-Duplicati.Library.Main.Operation.TestHandler-FailedToProcessFile\]: Failed to process file duplicati-i7aac0c7aaab94e8099ee752393504181.dindex.zip.aes\\r\\nCryptographicException: Failed to read 5 bytes, likely not an encrypted archive”,
“2025-08-27 09:09:12 +02 - \[Error-Duplicati.Library.Main.Operation.TestHandler-FailedToProcessFile\]: Failed to process file duplicati-i391fe28b10b247909be768dfc9e998a1.dindex.zip.aes\\r\\nCryptographicException: Failed to read 5 bytes, likely not an encrypted archive”,
“2025-08-27 09:09:53 +02 - \[Error-Duplicati.Library.Main.Operation.TestHandler-FailedToProcessFile\]: Failed to process file duplicati-i5a42c84e76d0433698c3b5ceb9102b1b.dindex.zip.aes\\r\\nCryptographicException: Failed to read 5 bytes, likely not an encrypted archive”,
“2025-08-27 09:09:59 +02 - \[Error-Duplicati.Library.Main.Operation.TestHandler-Test results\]: Verified 18 remote files with 3 problem(s)”
\],
“BackendStatistics”: {
“RemoteCalls”: 35,
“BytesUploaded”: 16946391,
“BytesDownloaded”: 606332563,
“FilesUploaded”: 3,
“FilesDownloaded”: 15,
“FilesDeleted”: 0,
“FoldersCreated”: 0,
“RetryAttempts”: 12,
“UnknownFileSize”: 0,
“UnknownFileCount”: 0,
“KnownFileCount”: 4958,
“KnownFileSize”: 257264525407,
“LastBackupDate”: “2025-08-27T09:07:05+02:00”,
“BackupListCount”: 11,
“TotalQuotaSpace”: 0,
“FreeQuotaSpace”: 0,
“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”: “2025-08-27T07:07:05.538142Z”,
“Duration”: “00:00:00”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null
}
}

How can I resolve this issue?

BR

Sebastian

2

Hi @katzebrrr, welcome to the forum :waving_hand:

This means that the file that Duplicati is attempting to read has a length of less than 5 bytes, so it cannot be an encrypted archive.

Can you examine the file duplicati-i7aac0c7aaab94e8099ee752393504181.dindex.zip.aes and check what size it really has?

Also, what storage backend is this?

3

Hi @kenkendk,

All three files are actually missing on the backup target. Is there any way to rewrite them or what do I need to do to repair this?

I backup to a Raspi.

BR

Sebastian

4

You can try the “repair” method found under “Database…” menu.
If it is only index files that are missing, they can be recreated.

If you are also missing dblock files, then you (most likely) need to use the purge-broken-files command which is not currently well integrated into the UI.

There is an explanation here:

5

Hi @kenkendk,

Since only dindex-files are missing, I tried the repair function but this doesn’t seem to be aware of anything to do:

        {

“MainOperation”: “Repair”,
“RecreateDatabaseResults”: null,
“ParsedResult”: “Success”,
“Interrupted”: false,
“Version”: “2.1.0.5 (2.1.0.5_stable_2025-03-04)”,
“EndTime”: “2025-09-11T14:28:30.8906516Z”,
“BeginTime”: “2025-09-11T14:28:30.1642743Z”,
“Duration”: “00:00:00.7263773”,
“MessagesActualLength”: 4,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: [
“2025-09-11 16:28:30 +02 - [Information-Duplicati.Library.Main.Controller-StartingOperation]: Die Operation Repair wurde gestartet”,
“2025-09-11 16:28:30 +02 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: List - Started: ()”,
“2025-09-11 16:28:30 +02 - [Information-Duplicati.Library.Main.BasicResults-BackendEvent]: Backend event: List - Completed: (4,87 KB)”,
“2025-09-11 16:28:30 +02 - [Information-Duplicati.Library.Main.Operation.RepairHandler-DatabaseIsSynchronized]: Destination and database are synchronized, not making any changes”
],
“Warnings”: ,
“Errors”: ,
“BackendStatistics”: {
“RemoteCalls”: 1,
“BytesUploaded”: 0,
“BytesDownloaded”: 0,
“FilesUploaded”: 0,
“FilesDownloaded”: 0,
“FilesDeleted”: 0,
“FoldersCreated”: 0,
“RetryAttempts”: 0,
“UnknownFileSize”: 0,
“UnknownFileCount”: 0,
“KnownFileCount”: 4991,
“KnownFileSize”: 257865931164,
“LastBackupDate”: “2025-09-11T16:13:00+02:00”,
“BackupListCount”: 16,
“TotalQuotaSpace”: 0,
“FreeQuotaSpace”: 0,
“AssignedQuotaSpace”: -1,
“ReportedQuotaError”: false,
“ReportedQuotaWarning”: false,
“MainOperation”: “Repair”,
“ParsedResult”: “Success”,
“Interrupted”: false,
“Version”: “2.1.0.5 (2.1.0.5_stable_2025-03-04)”,
“EndTime”: “0001-01-01T00:00:00”,
“BeginTime”: “2025-09-11T14:28:30.164278Z”,
“Duration”: “00:00:00”,
“MessagesActualLength”: 0,
“WarningsActualLength”: 0,
“ErrorsActualLength”: 0,
“Messages”: null,
“Warnings”: null,
“Errors”: null
}
}

The list-broken-files command only gives back:

Listing remote folder …

Return code: 0

In the end, everything remains the same, the problem doesn’t get solved.

Am I doing something wrong here?

BR

Sebastian