How do I solve the error "We cannot convert the value null to type Text"?

[anoniem]

Hi guys, the dashboard I created is linked to an Excel source and everything was working fine, but now the dashboard won't refresh anymore, because I get an error in the Power Query. Could it be due to a change in the source Excel file or is it an error in the Power Query? Because two weeks ago, everything was working perfectly 😞

Thanks

[UjjawalTyagi518]

hi @anoniem,
As you said you have connected through a excel data source, and you are getting this error.
it is happing because the data which you are getting from the excel file have some nulls, and when it connect to power query for refresh, the query will apply the same steps which u already did will formating and editing the excel file.
SOLUTION 
You can replace the value from null to 0 in your excel, then this error will be resolved.
let me know if that works for you!
thanks 

[anoniem · Accepted solution]

Dear UjjawalTyagi518, thank you for the suggestion. It turns out there were two columns added to the source Excel file by someone and these were of course not accounted for in the Power Query Editor in Power BI. So I manually typed in these column names in the steps and the dashboard works again!