https://www.nuget.org/packages/Thinktecture.IdentityManager/
The owner has unlisted this package. This could mean that the package is deprecated or shouldn't be used anymore.
Why is unselected? Is it no more in use? How can I now use IdentityManager with Thinktecture Identityserver3?
Looks like that was a beta3 version that has been unlisted in favour of beta 5-4:
https://www.nuget.org/packages/IdentityManager/1.0.0-beta5-4
I too will have to update... Not sure why they removed 'Thinktecture' from the package name (now it is just IdentityManager)