Problem with toolbox conversion URL

@dariok, @sika: We just tried to do a conversion on exist3 via the following URL:

However, eXist3 can't be reached at the moment (as also eXist2, which we assume is still in maintanance)

We also tried HTTP with port 8080:

With HTTP and port 8080 we can reach eXist3 but we get an HTTP 404.

We also tried the conversion with exist:

and get the error below:

Would you have an idea what could cause this error or how we could use the command with eXist3? Thanks in advance!