refresh failure

Thanks for the responses!

I did find the problem.

All the help documents for this error message, as well as solutions that other people seem to have to this problem, all had to do with the point of contact between Power BI and the data on the server (the SQL server settings were wrong or in some kind of conflict with the data types in BI, the version of the Gateway software (or Power BI itself) was outdated, there was a piece of data in one of the fields on the server that was a mismatch with the column type that it was being imported into, or some transformation of a column at the moment of refresh (using Power Query) was causing an error of data type, etc...).

However in my case, the error turned out to be that when I was in the Data view in Power BI Desktop (not Power Query), in "Column Tools" I had changed a column from data type "Text" to "Whole Number."

This did not cause a problem for a while. But after I used that column in a visual it started causing a problem. It did not cause in a problem in Power BI desktop. It did not cause a problem when I refreshed the report using Power BI desktop. It did not cause a problem when I published the report... it only caused a problem when I tried to refresh the published report. And the error message suggested the problem was with the server or in Power Query... not in a column transformation in the Data view.

So, I post this here so that it may be of use to someone else trying to figure out why their report is not refreshing.