Forum Discussion

RezaAssadi's avatar
RezaAssadi
Microsoft Employee
1 year ago

Getting transient Null Exception when refreshing a data source

I keep getting the error below when I do a full refresh on my Power BI report. However, refreshing the data source individually works without any issue. 

OLE DB or ODBC error: [Expression.Error] We cannot apply field access to the type Null.
How come the refresh only fails when I refresh all data sources across the report? And how can I see what the offending column is?
Need Help

3 Replies

  • vojtechsima's avatar
    vojtechsima
    Super User
    1 year ago

    RezaAssadi hello,

    do you have some dependency on some tables, or are you waiting for some query to finish before you get values for another one, that's the only thing I can think of.

    • RezaAssadi's avatar
      RezaAssadi
      Microsoft Employee
      1 year ago

      I do have different references between different tables. However, that used to work just fine before and I am not entirely sure why it would only break if I refresh all Data Sources at once (and not when I just refresh this one data source). What's more challenging is that there are no error logs telling me which column has a null reference and where that null reference is. I verified the underlying query and confirmed none of the columns are null.

  • RezaAssadi's avatar
    RezaAssadi
    Microsoft Employee
    1 year ago

    I was ultimately unable to figure out the root cause of the issue and ended up rewriting a bunch of queries to make this work. The fact that PowerBI fails due to a null exception but never tells you what that null exception is feels really broken.