(21, ERR_INTERNAL)

This error is usually due to an unexpected shutdown of the application server.
Possible causes include:
- A configuration problem (of the WEB server, application server or application).
- A rights problem (for example, the user running the application is not the right one or he does not have sufficient rights).
- An error at the beginning of the application loading.
- An internal error not processed by the application server.
- In IIS, the Internet guest user configured for the website ("Authentication") is different from the user specified in "Handler Mappings".

The pipe has been ended. (109)