What is code 90 error?

The initial backup (to a NAS) I am creating keeps failing with error 90.

I cannot find any explanation anywhere for any of the error codes.

What is error code 90? and where can I find a list of error code explanations?


Error code 90 seems to be an error while accessing a file/folder.
Can you please provide the log of the backup.
Were you using cbu file backup or simple copy backup?


Hi Emanuel, many thanks for coming back to me. I was using a cbu backup, but I have since uninstalled CB and reverted to Retrospect.

  • Chris


I had error code 90 when comodo couldn`t overwrite prev copy of backup on network.


This error code means the file is used by other application.
We had similar reports of this issue.
The problem will be fixed in the next release.



Run 4.3.1 and I still get code 90 when we try to run CB to network NAS.
The first backup works fine but the next run get error code 90.