Troubleshooting problems signing in Blackboard


  • This article provides solutions to the two common problems regarding signing in Blackboard.

“Sign On Error”

  • Please note that Blackboard is only available to current CUHK staff and students. If you are an alumnus, you will see "Sign On Error" after signing in Blackboard, as you no longer have access to the system. If you would like to access any Blackboard courses, please contact the Instructor / TA / Support Staff of the courses and request their approvals for getting the course materials.
  • If you are a current CUHK staff or student and encounter "Sign on Error", please take the actions below:
    • Use a new “private/incognito/inprivate window” to visit, login the system via “CUHK Login”.
    • In case you are using a bookmark/favourite saved in your browser to access Blackboard, please check and update the bookmark location to 
    • You could also consider clearing all history, cache and temporary files in the browser that you are using. Relaunch it and access Blackboard again.

“Bad Request - Header Field Too Long”

Graphical user interface, text, application

Description automatically generated

  • Please check Blackboard Help: Browser Support to see if your browser is supported.
  • Please consider clearing all the browser temporary files, history and cache of your browser. Then restart the browser, and sign in Blackboard again.
  • Or, use a new "private/incognito/inprivate window" to visit Blackboard.

Enquires about 2FA (DUO Two Factor Authentication)

Incorrect user ID or password

  • Please refer to ITSC Website: Log in through CUHK Login Page (3. The login page keeps saying "Incorrect user ID or password. Type the correct user ID and password, and try again".)
  • If you still have question, please contact the support team at ITSC Service Desk (Account, Email & Access > General Enquiry > Computing Accounts and OnePass Password). 

Should you have further questions, please contact us at / ITSC Service Desk (