The website or application you're uploading to might only accept specific file formats for images, such as JPG, JPEG, or PNG. Double-check the website's instructions or FAQs for the exact formats allowed.

Sometimes, special characters in the filename can cause issues. Try renaming the file to something simple without spaces or special characters.

There might be a maximum file size limit for uploaded documents. Reduce the size of your marksheet photos if they exceed the limit.

There are many free online tools and apps that can help you reduce the file size of your images without significantly affecting quality.

Sometimes, corrupted cache or cookies in your browser can interfere with uploads. Try clearing your browser's cache and cookies before uploading again. If the issue persists in one browser, try uploading from a different web browser to see if it makes a difference

I hope it helps!