I’m having the same issue. MP4 files that were previously shared and inspected by ChatGPT are now accepted by the interface, but can’t be accessed by ChatGPT’s processing environment.
When I attach an MP4, the attachment appears normally in the conversation. On ChatGPT’s end, the upload is recognized and assigned a file ID and a local /mnt/data/ path. However, when ChatGPT attempts to access that exact path to inspect the video, the file is not present. Attempts to read it with tools such as ls, file, or ffprobe therefore fail with a “No such file or directory”/file-not-found result.
The apparent sequence is:
User upload → attachment successfully registers in the conversation → file ID/path is created → actual file does not reach the processing environment.
This is different from a codec/decoding failure because ChatGPT never receives an accessible file to decode.
Troubleshooting/tests performed
I tested multiple independent variables to determine whether this was caused by my files or upload method:
• Multiple unrelated MP4 files were tested, not just one export.
• The MP4 sizes ranged from 405 KB - 4.1 MB. Every MP4 failed with the same result.
• Much large PNG files (2-3x larger) transferred successfully, ruling out file size as the cause.
• The PNG files were uploaded individually and immediately accessible to ChatGPT.
• HTML and CSS files were also successfully accessible.
• Renaming the MP4 did not change the result.
• Re-uploading/-exporting did not change the result.
• ZIPPING files did not help.
• A couple of new conversations were started to test the problem and had the same result, so it doesn’t appear to be caused by an old or overloaded chat.
• My account file storage was checked and is below the limit (5.11 GB of 20 GB used).
• I tested both dragging/dropping the file into the chat and sharing the file through “Add photos and files” and encountered the same failure.
ChatGPT was previously able to review my MP4 assets for a project I’ve been working on since the beginning of August and there was no problem, but suddenly, it was unable to access these files (it is not a problem with my account or the chat.)
Based on my tests, I suspect there is a bug in the attachment-to-processing-environment handoff for MP4/video files, instead of an issue with file size, filename, account storage, conversation age, upload method, or the individual video export because the frontend successfully accepts the MP4 files and ChatGPT receives metadata identifying the attachment, but the corresponding binary file is missing from the processing environment.
If others experiencing this issue are seeing the same “attachment exists/file ID exists, but assigned local file path does not” behavior, that may help narrow down where the regression is occurring.