Ok this is just my 2pence worth as I have not yet upgraded to 2.9.0…but first off is this professional or community? If professional I assume your license file is still valid and covers you to this release date? You say you removed the 2.5.3 folder…just for paranoya sakes when you import-module universaldashboard -requiredversion 2.9.0 into your script just to be sure it is loading the 2.9.0 version…also copy your .lic file into the net472 folder…I have seen numerous issues on 2.9.0 being raised in the forum, hence I delayed the upgrade…I’m running 2.8.1 now on IE and works great
Universal Dashboard version 2.9.0 has been working great for me on both local and thru IIS, when Adam releases a new version its basically included a fixes for issues has been reported but there is no changes to the core of the system until recently when the 3.0 project started.
so when you are testing version 2.9.0 start by uninstall-module the version you currently have and then install-module universaldashboard.
prepare your dashboard.ps1 file and open your browser and make sure to delete cache and test your dashboard.