Welcome, @Amy_uma
This error
seems like a server issue. Have you tried a rerun yet? Please do that first if you haven’t.
If the error is persistent, you can share back your work for feedback and troubleshooting help here. How to share you history is explained here, and you can post that link back in a reply.
And as an example, I started up a test run with the tool at the UseGalaxy.eu server. Maybe it helps, too?
Let’s start there, and let us know if you are able to solve this yourself, too! 