I just opened a project made in unity version 2018.1.1f into Unity version 2020.1.1f I know opening the older projects is not supported by Unity but it opened fine.

The only problem is that it is giving an error which looks like this-enter image description here

What I tried:

  1. checking the script onetizationPlatform.cs to ensure nothing is wrong in it
  2. checked that there's no two files with same name unitylifecyclemanager
  3. doing point 2 with unityengine.advertisement.editor
  4. deleting unityengine.advertisement.editor which caused another error so I had to restore it back
  • 2
    \$\begingroup\$ While I haven't experienced this particular error myself, I have resolved similar errors after updates by checking the package manager and making sure all packages are up-to-date. \$\endgroup\$
    – Philipp
    Jan 3, 2021 at 5:36
  • \$\begingroup\$ Is it possible UnityEngine.Advertisements.Editor used to be a standalone package and is now part of UnityEngine.Advertisements? (which would then conflict with the one still in your project). Since the latter has a higher version than the more specific one..? \$\endgroup\$
    – D.Kallan
    Jan 4, 2021 at 15:30
  • \$\begingroup\$ I've had this problem before with some other package, and it was caused because I had installed package X manually, but it was also a dependency of some other package. So I had two versions of the same package. I solved it by removing the manually installed package and using the one that was the dependency. \$\endgroup\$
    – Eldemarkki
    Jan 4, 2021 at 15:49
  • \$\begingroup\$ Sorry but I didn't installed any package manually and also made sure that all of my packages are up to date \$\endgroup\$ Jan 4, 2021 at 16:01
  • 1
    \$\begingroup\$ @D.Kallan Thanks mate! The problem is quite similar to mine,and maybe doing this will fix it. I'll update you about whatever happens \$\endgroup\$ Jan 5, 2021 at 13:36

1 Answer 1


I fixed the problem by first removing unity advertisements from package manager and then deleting every single advertisement or monetization related file from my project

After that I reinstalled unity advertisement from package manager which first gave 2-3 errors which were clearable and then everything started working nicely.


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