"Object reference not set to instance of an object" error

[Anonymous]

Overall issue: every time I refresh report, I get an error pop-up stating "Object reference not set to instance of an object". On my individual queries, the listed cause for the query being halted is "OLE DB or ODBC error: Exception from HRESULT: 0x80040E4E". The query recieving this error (and halting all refresh) is not consistent from refresh to refresh. I am able to successfully individually refresh every query.

Context: I am building a report with excel files and a SQL database as data sources. One of my excel files is a set of related but inconsistently formatted tables, where I individually query each table to change them from a wide to uniform long format, and then I use a reference query to combine all of the data into one long table. These Queries work perfectly in Power Query, and when run individually (including when I refresh just the reference query). I have verified my network connections to all these data, and I am working soley on PowerBI Desktop, with a PowerBI Pro license, and I have not yet tried uploading this report to see how it runs on PowerBI service.

I have searched forums and found that some people had errors like this in relation to data being in the wrong encoding in the excel sheet, errors with data sources and network connections, errors created by new releases or updates to PowerBi (circa 2017), and one suggestion that it was related specifically to data with null values. I have done my best to investigate these. Is there any established understanding now of what this error means, and what I can do about it? 

My hunch is that this is somehow related to PowerBI failing to refresh the reference query in the right order. 

Any help is appreciated. I have a more full stack trace I copied from this error - happy to post it here is someone more experienced with interpretting PowerBI stack traces could help me interpret it.

[Greg_Deckler]

You could check the Issues forum here:

https://community.powerbi.com/t5/Issues/idb-p/Issues

And if it is not there, then you could post it.

If you have Pro account you could try to open a support ticket. If you have a Pro account it is free. Go to https://support.powerbi.com. Scroll down and click "CREATE SUPPORT TICKET".