By Justin Doughty
Something I noticed on my own Revit 2018 Installation was that when the help icon was pressed, it took you to a URL that was not found. I simply worked around this by changing the last letter of the URL to U, to read ENU.
However, to permanently fix this, go to:
C:\Users\**YOUR USERNAME**\AppData\Roaming\Autodesk\Revit\Autodesk Revit 2018
Then find the Revit.ini file:
Open the Revit.ini File with Notepad or similar, and add the following line to the [Documentation] Section:
Now Restart Revit, click on the help icon and it should direct you to the correct online help page.
For more information on this refer to the Autodesk article below: