I encountered into the same issue.

I was running the tika server at http://localhost:9998. At the same time I called this address within the Open WebUI setting.

If you are trying to call anything within the localhost:3000, it becomes your 'dependency' for hosting the local service. You need to make sure that all of the 'dependencies' are running properly.

So in my problem, I tried to restart the tika server and the localhost:3000 can be accessed then.

I hope this can help solve the issue.