Please try the followings:
Logon to the web interface of this backup account

Go to the [File Explorer] page and browse to the directory reported that contain this problem (or some other directories)

Check if there are any filenames containing strange characters and delete them

Try backup again.

Also, please try increasing the "connectionTimeout" attribute within the "Connector" tag inside [OBS Home]\conf\server.xml to a larger value (e.g. connectionTimeout="180000" or connectionTimeout="600000"). This should help solve the problem.