Gateway Refresh Fails on "Ghost" Column

[irhyne]

I have a report pulling from a SQL database that works great on desktop and had been working fine on the PBI service until a couple of days ago. Suddenly, it began failing on a data mashup error claiming an invalid column name. Normally, this is an unannounced change in the DB naming convention, so I downloaded to the desktop, refreshed the dataset (which refreshed fine) to ensure I had the latest metadata including all column names, and published back up to the service. 

Same failure.

On investigation, the column name it is throwing is this: 

"value":"Invalid column name 't0_0'.<\/ccon>"}},

Neither I nor my DBA would ever use such a name for a column. Essentially, it seems the service has gone looking (or found) a ghost column. 

Any help would be appreciated.

[mattiasdesmet]

Excellent! Looked indeed a bit like some generated column, glad you discovered it

[irhyne · Accepted solution]

I just found and fixed the issue. It seems to be a PowerBI Service error. The query had several transforms, two of which included a table sort (not really necessary, but were there for the builders clarity in the construction phase). This seems to create a temporary column header "t0_0" which did not then go away but was invisible on load. When I removed the sort step from power query and re-uploaded, the error was gone. 

[mattiasdesmet]

Did you do any SQL Profiling on the query being sent out from the service? Perhaps it helps to narrows down where this occurs (or does this happen immediately when refreshing?)

Can you post the full error message?

Do you have different datasources configured on the dataset in the service through a gateway?