5.1 UNET components does not exist after project upgrade from 5.0

Unity Engine
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1

I have updated the project to 5.1, but there is no components of the new network.
However, another project successfully updated to version 5.1 and components of the new network are available in this project.

I tried to export a prefab with Network Manager component, but in place of this component shows text information about the non-existent script.

What should I do?

2

I’ve had similar issues with the 4.6 UI Components on upgrade, Try deleting the project library folder, and reopening unity. (make sure you have .meta files in your Assets folders before doing this so unity can rebuild the project)