What should I do if I'm having trouble uploading documents for the sandbox COE in Thailand?

Users facing challenges uploading documents for the Sandbox Certificate of Entry (COE) in Thailand can try several solutions: 1) Switch to a different browser, preferably Chrome, which appears to work better. 2) Check and adjust your region settings as a wrongly formatted date could cause issues. 3) Ensure that the file size is reasonable to avoid timeouts. 4) Remember to press the upload button after selecting your document. 5) If you have antivirus software like McAfee, consider its impact on the upload process. If problems persist, logging out and reattempting the upload might also help.