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Fixed in 2021.1.X

Fixed in 2019.4.X, 2020.1.X, 2020.2.X



Found in

Issue ID




Unity fails to open project with error: Failed to resolve packages: An operation that requires exclusive access to the project..



For some users Unity is failing to open and shows the following error:

Failed to resolve packages: An operation that requires exclusive access to the project is already running and must be completed before another can be started.. No packages loaded.

This issue happens only if the resolve package operation takes over 2 minutes to complete. Users will find this failure randomly while opening their projects.

Comments (12)

  1. D86bb436a0eaf850042c1dcb2da080e1?d=mm


    May 28, 2021 08:51

    2021.1.7f1 (64-bit), still occurs

  2. 4e2dd3e2e8ac412704504868c8b35e9f?d=mm


    May 17, 2021 04:37

    2020.3.4 still the same issue is there

  3. 8ef6434be3a2e42fce1d59b2d2339ceb?d=mm


    Apr 14, 2021 12:17

    2020.1.10, still occurs

  4. 27e48159b1ed6c45da66739348b084e9?d=mm


    Nov 20, 2020 00:31

    2019.4.14f1 same

  5. 9bfa545cc50ebbc621ab399dd3eae318?d=mm


    Nov 18, 2020 05:11

    I had this problem in 2020.1.13f1. My workaround was selecting Continue instead of Retry or Quit, then the project opened with a lot of errors from missing packages, then I opened a scene of the game and right clicked on a random asset in the Project tab/window and then selected Reimport All.

  6. 6924cc55b872c64217b3c1a75a0de8a7?d=mm


    Nov 17, 2020 15:42

    I installed Unity 2019.4.14f1 yesterday and this error occurs each time I open Unity. The description says it's fixed in 2019.4. Is that accurate? Is there a patch I need?

  7. 5e6feb8dd2036eea0b4116d01050fb3b?d=mm


    Nov 16, 2020 22:54

    I also have this problem in 2020.1.11f1 can't figure out how to resolve it.

  8. Da612f88eb161e5dc45d6d217d308080?d=mm


    Nov 16, 2020 05:27

    I'm currently on 2019.4.14f1 and this error is still occurring for me

  9. D5d7b4ba4213de930b6b78f22c647931?d=mm


    Nov 15, 2020 10:32

    Still persist in 2020.2.0b11

  10. 2a98830734499333f5e18bbc9e6e1a70?d=mm


    Nov 12, 2020 11:16

    Still happens in 2020.2b10

    Because I'm on a very slow internet connection, I frequently have problems with Unity and the Package Manager (like checking for updates in the foreground when browsing, instead of in the background and displaying what's cached).

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