That is a server error and you will need to speak to your hosts as to what the problem is. It may be a temporary problem in that your hosts were doing some maintenance so trying again might work.
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I had a similar issue recently. I was doing a test backup and restore. The system error was caused by the number of database requests made in a very short time by a single user. It looked like the site was being DDOSed and the automatic system protection kicked in and denied all further access for 30 minutes.
Contact your host and tell them your intentions and they should temporarily disable the anti-spam protection to allow you to complete your work.