What is another debugger already attached error, and how do I solve it?

Ui.Vision Bug Reports
1

I’m getting this error while uploading a file and AI is asking me to raise in the forum, its currently blocking me from moving forward, please help.

  • Another debugger is already attached to the tab with id: 890902103. (line 72) (Runtime 13.41s)
2

The cause: file upload in the browser goes through Chrome’s debugger API (the DOM.setFileInputFiles call in debugger.js:152). Chrome lets only one client debug a tab at a time.

Something else already holds that tab, so Ui.Vision cannot attach and the upload on macro line 72 fails. Nothing is wrong with your macro.

How to get unblocked, try in this order:

  1. Close DevTools on that tab if it is open (press F12 there). DevTools takes the debugger slot.

  2. Look at the top of that tab for the bar “… started debugging this browser”. It names the holder. Press Cancel on that bar and the tab is released, whoever held it. If it says Ui.Vision, please let me know.

  3. Disable the other automation extension for this run. Claude in Chrome is the usual suspect, Selenium IDE, Chrome’s Recorder and screen-recording extensions do the same thing.

  4. Close the tab and open the page again in a fresh tab. A new tab has a new id with nothing attached. This works even when the holder is a stale Ui.Vision session, and it is the fastest fix if steps 1 to 3 show nothing.

  5. Check for two Ui.Vision installs at chrome://extensions. A store copy and an unpacked dev copy fight over the same tab. Disable one.

  6. If the upload still must run with the other debugger present, the fallback is the desktop tier: click the upload button and type the file path into the OS file dialog with uiv.desktop.type, which needs the XModule

3

Thanks, the tab is held by ui vision itself, what should I do in this caseScreenshot 2026-09-13 at 11.56.49 AM

4

Thanks for this feedback!

Workaround: press Cancel on that bar. That releases the tab, and the upload run will work again. If the bar is gone but the error stays, close the tab and open the page in a new tab, then run the macro again.

Real solution: We will fix this bug with the next update in a few days.

Fixed now with V10.0.270