On my windows machine, in the app store settings under "Upload local manifest", after selecting a .json manifest file and pressing "Add manifest" the driver-app-store refuses to upload it with the error "Incorrect file type". On checking, the browser reports the filetype as "text/plain" and the app-store is checking for "json" in the mime type. This may well work on other platforms, but browser/system mime type guessing is known to be brittle, especially on Windows see note
On my windows machine, in the app store settings under "Upload local manifest", after selecting a .json manifest file and pressing "Add manifest" the driver-app-store refuses to upload it with the error "Incorrect file type". On checking, the browser reports the filetype as "text/plain" and the app-store is checking for "json" in the mime type. This may well work on other platforms, but browser/system mime type guessing is known to be brittle, especially on Windows see note