AdminUI shares a database schema with IdentityServer4. The schema needs to up upgraded to 2.3 for AdminUI 2.3 to work. AdminUI can perform the schema upgrade for you depending on your current scenario, select the most appropriate outlined below.
I have IdentityServer4 2.2 or below and no installation of AdminUI
You will need to migrate the database to the 2.3 schema. The simplest way is to upgrade your IdentityServer to 2.3 and generate the migrations, you can find out how here.
I have IdentityServer4 2.0 - 2.2 and AdminUI 2.0 - 2.2 installed
If you previously requested that AdminUI run the IdentityServer migrations then continue to do so, otherwise, you will need to upgrade your IdentityServer4 to 2.3 and generate your own migrations, you can find out how here.
I have IdentityServer4 2.3 installed and no AdminUI
Install AdminUI, and ensure IdentityServer migrations are turned off.