I keep encountering errors when trying to upgrade to the most recent version of Vuforia from within Unity. From what I can tell, everything works fine when enabling the Vuforia module on the 2018.3.6 unity installation, but upgrading from the existing version to version 8.1.10 from within a Unity project causes problems.
1) Install Unity 2018.3.6f1 with Android and Vuforia modules.
2) Open a project (I'm using an empty project with Vuforia Core Samples imported from the Asset Store) and check "Vuforia Augmented Reality Supported" in XR settings. Vuforia version will be 8.0.10, and going to Window->Vuforia Configuration will prompt to upgrade to 8.1.10.
3) Click the upgrade link from the Vuforia Configuration object. This will download a zip folder (VuforiaSupportInstaller-Windows-8-1-10) containing the file "UnitySetup-Vuforia-AR-Support-for-Editor-2018.3.exe".
4) Close the Unity project and run the UnitySetup file, pointing it to the Unity 2018.3.6f1 installation (in my case, C:\Program Files\Unity\Hub\Editor\2018.3.6f1). Confirm that the upgrade was successful and the files in C:\Program Files\Unity\Hub\Editor\2018.3.6f1\Editor\Data\PlaybackEngines\VuforiaSupport have been modified.
5) Reopen the unity project. The error messages seen in the image (Errors2018_3_6.png) appear, and there is no link to Vuforia Configuration or Vuforia GameObjects from the Unity top bar. Scripts (including Vuforia Configuration) appear as Missing in the inspector. "Vuforia Augmented Reality Supported" in XR settings is still enabled, and unchecking/rechecking it doesn't seem to prompt any changes.
I have also tested this on a non-Hub Unity 2018.3.6f1 installation with the same result.
I have tested this on Unity 2018.3.14f1 as well - it started with Vuforia version 8.1.7 instead of 8.0.10. After upgrading to 8.1.10 using the same method described above, it shows the 3 errors in the second image (Errors2018_3_14.png).
I am using Windows 7 - please let me know if you need any more information.
Thank you for your help!