Getting new Report Builder 401 error.` Report Builder Hell

[Criamon]

Hello all.  I've got a paginated report that is now crashing Report Builder.

So I go to the service and I have a data set I just created and I had the service create the .rdl.  I open it and it's got the BI Service workspace data source in there. 

But when I try to edit the data source set I get:

The remote server returned an error: (401) Unauthorized.

No re-entering of credentials fixes anything.  Monkeying with the timeout setting doesn't help.  On line, I've verified my credentials work fine.  Also, editing from those data sources in that workspace works fine in Power BI Desktop.  

So to check the data source, I choose "Edit Datasource"  and as soon as the "Select a dataset from the Power BI service" dialog box opens I get "Undocumented error" and under "Details" I get:

Expecting element 'root' from namespace ''.. Encountered 'None' with name '', namespace ''.

When I exit out of the error Report Builder crashes.  (sigh)

Breaking out the best Google-Fu I can muster the nearest related help I could find was this:

https://whitepages.unlimitedviz.com/2019/10/fixing-power-bi-report-builder-connection-errors/

In that post it looks like he's describing not *exactly* the same thing but something very similar.  He explains: "What is happening in both of these cases is that the token acquired from the Power BI service has expired, and Report Builder does not automatically fetch a new one. There are a couple of ways to deal with this problem."

His suggested solutions don't work for me.

But thinking about this idea of refreshing the token, I then tried logging in and out of the service, rebooting the local machine, regenerating the .rdl after re-logging on, logging out and logging back into the Sharepoint site that my data is coming from, "Repairing" my Report Builder install.

None of those actions helped my situation.

Any ideas what I should do next?

Also, it should be noted I have two windows / BI accounts - one with my regular work account and another set up by this specific client. 

Thanks in advance for anyone who can get me out of Report Builder hell.

[Criamon · Accepted solution]

OK, looks like the real fix is to switch BI accounts in Report Builder and then switch back.  That seems to fix it every time.  That's a fix, but that it's occurring and recurring is a bit disconcerting.  

[Criamon]

OK.  Somehow I "fixed this".  What I tried is downloading a .rdl file from my other account.  In Report Builder I switched accounts and it seemed to work.   Then I closed that and opened up the problem report, switched accounts in Report Builder, and now it seems ok.  

Still wondering about what was happening under the hood though, which would be useful for future troubleshooting, so any illumination people can provide will still be apreciated.

Thanks.

[Criamon]

Ugh.  Now it's broken again.  Still need help.  Not sure what's going on.

[fomoisreal]

Any fix on this @Criamon ? on the same boat too