https://community.fabric.microsoft.com/t5/Report-Server/SharePoint-List-and-Data-Transformations-Authentication-Errors/m-p/854535#M12273 <P>We discovered today that when making a connection to a SharePoint list and running certain data transformations it would continuously prompt for the users authentication and throw authentication errors.&nbsp; &nbsp;We checked the SharePoint logs and noticed nothing was being passed and after troubleshooting found that it appears to be related to the number of columns in the list.</P><P>&nbsp;</P><P>This particular list had 251 columns, connecting to it worked fine but adding unpivot or right outer join causes the authentication errors to appear.&nbsp; &nbsp;Removing all but 5 columns from the query resolved the issue, so it appears that some data transformation can not handle large number of list columns.&nbsp; &nbsp;</P><P>&nbsp;</P><P>Anyone run in to this before?&nbsp; The obvious workaround is to remove the columns that were not needed but wondering if there is a hard limit for data tranformations?&nbsp;&nbsp;</P> Wed, 27 Nov 2019 14:23:29 GMT Anonymous 2019-11-27T14:23:29Z https://community.fabric.microsoft.com/t5/Report-Server/SharePoint-List-and-Data-Transformations-Authentication-Errors/m-p/854535#M12273 <P>We discovered today that when making a connection to a SharePoint list and running certain data transformations it would continuously prompt for the users authentication and throw authentication errors.&nbsp; &nbsp;We checked the SharePoint logs and noticed nothing was being passed and after troubleshooting found that it appears to be related to the number of columns in the list.</P><P>&nbsp;</P><P>This particular list had 251 columns, connecting to it worked fine but adding unpivot or right outer join causes the authentication errors to appear.&nbsp; &nbsp;Removing all but 5 columns from the query resolved the issue, so it appears that some data transformation can not handle large number of list columns.&nbsp; &nbsp;</P><P>&nbsp;</P><P>Anyone run in to this before?&nbsp; The obvious workaround is to remove the columns that were not needed but wondering if there is a hard limit for data tranformations?&nbsp;&nbsp;</P> Wed, 27 Nov 2019 14:23:29 GMT https://community.fabric.microsoft.com/t5/Report-Server/SharePoint-List-and-Data-Transformations-Authentication-Errors/m-p/854535#M12273 Anonymous 2019-11-27T14:23:29Z