System.TypeLoadException when configuring DbContext

Exception details

System.TypeLoadException
  HResult=0x80131522
  Message=Method 'PopulateDebugInfo' in type 'Npgsql.EntityFrameworkCore.PostgreSQL.Infrastructure.Internal.NpgsqlOptionsExtension' from assembly 'Npgsql.EntityFrameworkCore.PostgreSQL, Version=3.0.0.0, Culture=neutral, PublicKeyToken=5d8b90d52f46fda7' does not have an implementation.
  Source=Npgsql.EntityFrameworkCore.PostgreSQL
  StackTrace:
   at Microsoft.EntityFrameworkCore.NpgsqlDbContextOptionsExtensions.UseNpgsql(DbContextOptionsBuilder optionsBuilder, String connectionString, Action`1 npgsqlOptionsAction)
   at ...OnConfiguring(DbContextOptionsBuilder optionsBuilder)
   at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider()
   at Microsoft.EntityFrameworkCore.DbContext.get_DbContextDependencies()
   at Microsoft.EntityFrameworkCore.DbContext.Set[TEntity]()
   (further StackTrace is omitted)

Environment

Microsoft.EntityFrameworkCore 3.0.0-preview.19074.3
Npgsql.EntityFrameworkCore.PostgreSQL 3.0.0-ci.1451

[calexander3]

@CumpsD There is a prelease package that solved that issue for me.

[koryphaee]

After the upgrade I couldn’t connect to my old database. Turns out the PostgreSQL option “standard_conforming_strings” has to be “on” or Npgsql refuses to connect. Since PostgreSQL 9.1 “on” is the default value but apparently in our internal database this was manually turned off.

The following statement solves the issue:

ALTER DATABASE <db> SET standard_conforming_strings TO 'on';