ChatGPT file upload stuck loading? The 4 causes, and the 1 minute test

Two very different failures wear the same spinner, and the fixes have almost nothing in common. Sorting out which one you have takes about a minute and saves you from changing the wrong thing.

The two failures that look identical

The file never attaches. The progress indicator crawls, freezes, or resets, and no file chip appears next to the composer. Nothing reached OpenAI. This is a transport problem: browser, extension, or connection.

The file attaches but the answer never comes. The chip appears, you send the message, and the reply sits there generating for minutes. The upload worked. What you are watching is ChatGPT trying to read a document that is heavy, long, or awkwardly structured.

The first is worth troubleshooting. The second is often just slow, and the cure is a smaller file rather than a fix.

The one minute test

1. Make a trivial file

   Create a plain text file with one sentence in it. This removes your document from the picture entirely.

2. Upload it in a fresh chat

   Not the chat you have been fighting with. A long conversation with several attachments already in it behaves differently from a new one.

3. If it fails, open an incognito window

   Chrome disables extensions in incognito by default, so this tests your extensions and your cached tab in a single step. Sign in and try the same tiny file.

4. If it still fails, check status.openai.com

   Uploads have their own incidents, and the app does not always make that obvious from the inside.

Extensions, the most common single cause

Anything that inspects or blocks network requests can break an upload halfway through. Ad blockers, privacy and anti-tracking extensions, script blockers and VPN browser extensions are the usual offenders. Other ChatGPT extensions matter too, since several rewrite the composer area of the page and can interfere with the file picker attached to it.

Once incognito confirms it, re-enable your extensions in small batches rather than one at a time. You will find the culprit in three or four reloads instead of fifteen.

When the browser or the tab is the problem

A ChatGPT tab left open for days accumulates state. The session token behind the upload request expires independently of the interface, so the page looks signed in while the upload quietly fails authentication.

Reload the tab with a hard refresh first. If that does not clear it, sign out and back in, then clear site data for chat.openai.com. Trying a different browser is a fast way to confirm the diagnosis before you spend time clearing anything.

When the file really is the cause

If a one line text file uploads and your document does not, work through these in order.

Cloud placeholder files. A file stored in iCloud Drive, OneDrive or Dropbox may exist locally only as a stub. The file picker shows it as though it were on the disk, but the browser has to pull it down before uploading, and on a slow connection that looks exactly like a hung upload. Right click the file, download or keep it locally, then upload again.

Size ceilings. 512 MB per file, about 50 MB for spreadsheets and CSV, and 20 MB per image. Files near these thresholds often stall rather than producing a clean error.

Length rather than size. Text and document files are capped at 2 million tokens, and spreadsheets are exempt from that cap. A long document can be modest in megabytes and still be far past what fits, which shows up as a very slow response instead of a rejection.

Password protected or damaged PDFs. An encrypted PDF cannot be read, and a partially corrupted one can hang the processing step. Open it, re-export it without protection, then try again.

Network causes worth ruling out

Upload speed is not download speed. A connection that streams video without trouble can still take several minutes to push a large file, and on a busy shared network it may never finish.

Corporate networks and VPNs add another layer, since inspection proxies routinely break large multipart uploads. If you are on a work laptop and a small file uploads while a large one never does, that is the signature. Try the same file on a mobile hotspot. If it goes through, the network is your answer and no amount of clearing browser data will help.

Stop retrying while you diagnose

Failed attempts count toward your allowance. The rolling cap is 80 files every 3 hours, and on Free it is 3 file uploads per day, so a file you retried a dozen times has spent a dozen slots on nothing. ChatGPT does not show how much of that rolling allowance remains, which is why the limit message so often arrives as a surprise right after a run of stuck uploads.

The practical order

Tiny text file in incognito, then status.openai.com, then extensions, then the browser session, then the file itself. That sequence puts the cheapest checks first and identifies the cause in a few minutes.

If the tiny file uploads everywhere and only your document stalls, stop treating it as a bug. The document is too big or too long for one upload, and splitting it is the fix rather than the workaround.