A file or image upload is refused

First, work out where the refusal came from. If the message appeared instantly, your browser or the app rejected the file locally without uploading anything. If it appeared after a progress bar, the service rejected it. The two have different causes.

Instant rejection: the file type or size is out of bounds

• The extension is wrong for the contents. A file named .jpg that is actually a HEIC image, or a .csv that is really an Excel workbook, gets rejected on inspection. Re-export it properly rather than renaming it.
• The format is not supported. Formats change over time and differ between the web app and mobile. Converting to a common format (PDF for documents, PNG or JPEG for images, plain text for anything textual) resolves most of these.
• It is too large. Compress, or split it. For a long PDF, splitting is usually better than compressing, because you also get better answers from smaller sections.

Rejection after uploading: server-side

• Retry once. Genuine transient failures happen, and the second attempt tells you whether it was one.
• Check your connection is stable rather than merely present; an upload that stalls at 90% is often a network problem, not a file problem.
• Check whether other uploads work. If a small text file also fails, the problem is your session or the service, not the file.
• Check the status page, linked from x.ai, before spending time on your own setup.

When it uploads but the answer ignores it

That is a different problem. The file arrived and the request was too vague; see Working with files, images and long inputs.

Things worth trying that people skip

• Paste text instead of a screenshot of text. More accurate, faster, and never refused for format reasons.
• Flatten the document. Scanned PDFs, password-protected files and documents with tracked changes or embedded forms behave unpredictably. Export a clean copy.
• Try the web app if mobile refuses. The surfaces do not always accept the same things.

What changes

Accepted formats, size ceilings and per-plan upload allowances all change without announcement. Nothing on this page states a specific limit for that reason, x.ai has the current ones.