Its been a while since you submitted this, hopefully you opened up a support ticket for this issue. But for those still referencing this question for their own issues, the answer lays MOST often in the arcgis server. If you restart the arcgis SERVER (not portal) windows service, this issue may clear up. The potential reasons for this are numerous and delve deeply into contingencies for how your environment is set up. However, if this does NOT clear up your issue, then your fastest way to have these contingencies addressed (and reduce risk of breaking things) is with a support ticket.
For those who'd like to dive a bit deeper, please check that your arcgis server federation validates with no errors from portaladmin
I.E. https://machine.domain.com/portal/portaladmin/federation/servers/validate
This "something went wrong" error is often a symptom rather than a cause because of its dependency on portal server and datastore all being fully functional and communicating correctly.
If your validation fails for any reason to include inaccessibility of the hosting url, persue that for your troubleshooting and you will likely resolve your "something went wrong" issue among other problems that may have yet to be discovered.
Note that you can get more informed information about these "something went wrong" errors by looking at the logs in the arcgis server manager from the same timestamp as that event. These are often infinitely more helpful in directing your diagnostics for this problem.
