Some files are backuped but very much files make this error:
Failed to process path: S:\scan\E-Mail 13 G-T00-1.jpg
Alphaleonis.Win32.Filesystem.UnrecognizedReparsePointException: I/O error occurred.
at Alphaleonis.Win32.Filesystem.Device.GetLinkTargetInfoCore(SafeFileHandle safeHandle)
at Alphaleonis.Win32.Filesystem.File.GetLinkTargetInfoCore(KernelTransaction transaction, String path, PathFormat pathFormat)
at Duplicati.Library.Snapshots.WindowsSnapshot.GetSymlinkTarget(String file)
at Duplicati.Library.Main.Operation.BackupHandler.HandleFilesystemEntry(ISnapshotService snapshot, BackendManager backend, String path, FileAttributes attributes)
this is from the server log (solved):
Volume Shadow Copy Service error: Unexpected error querying for the IVssWriterCallback interface. hr = 0x80070005, Access is denied.
. This is often caused by incorrect security settings in either the writer or requestor process.
That depends on who you trust. Robustness-wise I would recommend only using the AES encryption module, as that is built-in, and has a good track record.
GPG on the other hand, is much older (good for trust) but also difficult to use. The integration in Duplicati works by calling the gpg.exe executable, which is a potential security issue itself (i.e. an attacker installs a proxy gpg.exe that also logs the keys). But it also offers all the features that GPG has (various encryption methods, key strengths, etc).
I read that storing data and diffs on the same drive can cause problems. Did you try to move the location for shadow copies to a different, dedicated drive? You can check the location of your shadow copies by running vssadmin list shadowstorage from an elevated command prompt. Moving the shadow copy location to another volume is described here.