Did you use menu Help / Report a Bug as I suggested? I don't even know what operating system (Mac, Windows, Linux) you are using. It could also be helpful to attach a screenshot of the AlphaFold Run window.
On Mac with the current ChimeraX daily build I just ran AlphaFold prediction from ChimeraX and had no problems. The error you get means that ChimeraX cannot send the sequence to Google Colab. The way it sends the sequence is it runs some JavaScript code on the Google Colab web page shown in the AlphaFold Run window. So if your Google Colab web page looks different (not sure why, maybe you have Colab configured in some custom way), or if you have some permissions restriction that prevents ChimeraX from running that JavaScript in the Colab page, then that would explain the failure. Certainly something is different about your computing environment. Maybe it is network security restrictions at your site.
![[ChimeraX Issue Tracking System]](/trac/ChimeraX/chrome/site/ChimeraX-icon.svg){kind=icon}
