Thanks @ismcagdas
The problem have been solved, we changed the connection string after we've migrated to Postgresql
But now I have another issue when opening the Host project (mydomain.com/Ui/Login) from the browser, I got the following error:
InvalidCastException: Cannot write DateTime with Kind=Local to PostgreSQL type 'timestamp with time zone', only UTC is supported. Note that it's not possible to mix DateTimes with different Kinds in an array/range. See the Npgsql.EnableLegacyTimestampBehavior AppContext switch to enable legacy behavior.