If you are facing issues with generating JSON file you can check below things:
Step 1:You need to check that the release of BUSY is the latest one.
Step 2:You need to check for errors in transactions, HSN summary, and document summary. Make sure there are no errors in those sections, If there are any errors, you should correct them.
Step 3:if still same,Check the default path, it should typically go to C:/BUSYwin. If there is any issue with this path, create a new folder on your desktop location, provide the path for that location, and generate the JSON file,make sure JSON will generate successfully.