Error On Import

[dbszepesi]

I am getting the following when trying to import my JSON file:

Invalid dataflow structure. Exception Details: Token Comma expected. Start position: (249,1). End Position (249,3). Activity ID is [GUI]. Request ID is [GUID].

How can I find out where this is in the JSON file? Is that a row number (249)?

[nolockcz]

Yes, it is the line number.

[dbszepesi]

Visual Studio Code and Notepad both show pbi:mashup as a single monster column on line 8. If I look at line 250 after that, there is nothing weird there. Any chance that line number is counting lines in the pbi:mashup column?

[nolockcz]

I know, there is a long line but that's a format, which MS uses in the PBI dataflows.
It's complicated to help you without seeing the PBIX file :(