“Object reference not set to instance of an object” error

This can happen after a new installation if the location/workbook is considered not trusted. This seems to happen either because excel considers every workbook downloaded from internet as not trusted or just considers network location as such. When open any Tabular workbook you get the protected view strip on top of the excel workbook. If you click Enable editing – the workbook is reloaded, but this causes Tabular to show the “Object reference not set to instance of an object” error because it mess the loading events.
To fix that you can either add all Tabular locations to trusted locations in Excel-> Options -> Trust center or just disable protected view from Excel -> Options -> Trust Center ->Protected view -> uncheck “Enable protected view for files in untrusted locations” and/or uncheck “Enable protected view for files originating from the internet”