Two options: 1. Provide additional details like when you're seeing the error, what type of backup storage you are using if this is related to a backup or restore, platform and product version. 2. Send this over to support from the Tools | Diagnostic toolbar option and they can have a look at your log files to see what the issue is (this is probably the fastest way to resolution).

Hello,
This error might be caused by the lack of RAM to perform the backup. In this case, I'd recommend you to restart the server and try to run the backup in non-working hours when a server is not heavy loaded. Also, you can set memory limits on the memory option tab.