Unless you are upgrading to analysis services on SQL Server 2019, chances are you are going to have to review your DAX code and make some modifications as DAX on the other versions of SQL Server are not the same as Power BI. I was upgrading to AS on SQL Server 2016, there were some commands that I had to manual edit out of the JSON file. If you have any new DAX commands, take them out of your Power BI Model which means you will not have to manually edit the JSON file to remove them when the new commands are flagged as errors. Make sure your Power BI Model does not include commands such as SELECTEDVALUE, GENERATESERIES as well as all of the automatically generated date hierarchies. After your Power BI desktop file is clean, leave it running as you are going to need to have it running for the next step.
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