Since we just transitioned courses from Blackboard 8 to version 9, you may come across "Invalid HTML" error messages on some content items. (See Image Below)

With editing mode turned off, the content still displays as normal, but to get rid of this error message within editing mode you need to...
1. Click the double down arrow beside the item name to display the menu for that item and then click "Edit".

2. Once in the editing screen, click on the "Markup validation" icon.

3. Click "Ok" to close the the Markup Validation Report window that appears, and then click "Submit".
This should clear the invalid html message from that item.