Hello @Ace-7747 !
Welcome to Microsoft QnA!
The error message "Request headers must contain only ASCII characters" indicates that the request headers in your JSON file contain non-ASCII characters. To resolve this issue, you can try encoding your JSON file in ASCII format. In the Notepad++, try to convert the encoding of your file to ASCII. To do this, open your JSON file in Notepad++, click on the encoding and select "Convert to UTF-8" and see if it helps
Also try to import the schema on the source setting if applicable
I hope this helps!
Kindly mark the answer as Accepted and Upvote in case it helped!
Regards