If you were do backup in razuna admin page and there was an error with backup file , so you can remove the corrupted files and try to run the backup task again to make sure the new backup file created in properly.
This is most likely due to a memory problem, i.e. I suggest you increase
the memory allocation for Tomcat You can find all about it on the forum
here or on our wiki http://wiki.razuna.com
If you are using MySQL, I suggest to do backup on the shell instead if
within Razuna.