6.2.X EE, 7.0.0 DXP SP2, Master
Clicking on a tag in the Tags Navigation portlet will throw an error if there is a Message Boards portlet on the same page in which a post has been tagged with the selected tag and that post is opened while in "My Posts."
Steps to Reproduce:
1. Login as an admin.
2. Create a new page with a Message Boards portlet and Tags Navigation portlet.
3. Navigate to Site Admin and create a tag "tag1".
4. Post a new thread "Test" from the Message Boards portlet, add the tag "tag1" and save.
5. Select "My Posts" tab in the Message Boards Portlet. "Test" is displayed correctly.
6. In the same page select the tag "tag1" from the tags navigation menu.
"Test1" should be displayed since the post belongs to the current user and the post is tagged with "tag1".
An exception is thrown and no posts are listed.
Reproduced in ee-6.2.x: be2675cd9a275dd590e1e29a4e01333f1cac952b
Reproduced in ee-7.0.x: 7c6446039e9ce707cbd005210baa11d5df41da4b
Reproduced in master: 435e6348afab70bb3b54ad2edf762c627edd7f29