EF Core with SQLite on Mono: e_sqlite3 not found

entity-framework-core mono sqlite

Question

We are using Entity Framework Core 2.2.4 together with an SQLite database targeting .NET Framework 4.7.2. Following Nuget packages were installed:

Microsoft.Data.Sqlite
Microsoft.EntityFrameworkCore.Sqlite
Microsoft.EntityFrameworkCore.Tools

On my development machine (Windows 10) everything works fine but when trying to run the application with Mono on our 32-bit Linux machine, the following exception occurs:

FATAL UNHANDLED EXCEPTION: System.TypeInitializationException: The type 
initializer for 'Microsoft.Data.Sqlite.SqliteConnection' threw an exception. 
---> System.Reflection.TargetInvocationException: Exception has been thrown 
by the target of an invocation. ---> System.DllNotFoundException: e_sqlite3
at (wrapper managed-to-native) 
SQLitePCL.SQLite3Provider_e_sqlite3+NativeMethods.sqlite3_libversion_number()
  at SQLitePCL.SQLite3Provider_e_sqlite3.SQLitePCL.ISQLite3Provider.sqlite3_libversion_number () [0x00000] in <61bb3ca1db9c41ea88f280f0b1600d58>:0
  at SQLitePCL.raw.SetProvider (SQLitePCL.ISQLite3Provider imp) [0x00008] in <3d4b21fb9c764efbb11f6e3b02efff52>:0
  at SQLitePCL.Batteries_V2.Init () [0x00005] in <f5d9c86a14864b5d99b8bdece1b8292c>:0
  at (wrapper managed-to-native) System.Reflection.MonoMethod.InternalInvoke(System.Reflection.MonoMethod,object,object[],System.Exception&)
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00032] in <a89b9d7c1a66468eb33312af7ed3a74e>:0
   --- End of inner exception stack trace ---
  at System.Reflection.MonoMethod.Invoke (System.Object obj, System.Reflection.BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) [0x00048] in <a89b9d7c1a66468eb33312af7ed3a74e>:0
  at System.Reflection.MethodBase.Invoke (System.Object obj, System.Object[] parameters) [0x00000] in <a89b9d7c1a66468eb33312af7ed3a74e>:0
  at Microsoft.Data.Sqlite.Utilities.BundleInitializer.Initialize () [0x0002f] in <b46e232ade014524baa458345f270c50>:0
  at Microsoft.Data.Sqlite.SqliteConnection..cctor () [0x00000] in <b46e232ade014524baa458345f270c50>:0
   --- End of inner exception stack trace ---
  at (wrapper managed-to-native) System.Object.__icall_wrapper_mono_generic_class_init(intptr)
  at Microsoft.EntityFrameworkCore.Sqlite.Storage.Internal.SqliteRelationalConnection.CreateDbConnection () [0x00006] in <74192050a4d342039620dc7ef6678f71>:0
  at Microsoft.EntityFrameworkCore.Internal.LazyRef`1[T].get_Value () [0x00008] in <adf771f92e754fe1bb85c5850cd0c16b>:0
  at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.get_DbConnection () [0x00000] in <69f795dffc844780bfcfff4ff8415a92>:0
  at Microsoft.EntityFrameworkCore.Storage.RelationalConnection.Open (System.Boolean errorsExpected) [0x00000] in <69f795dffc844780bfcfff4ff8415a92>:0
  at Microsoft.EntityFrameworkCore.Sqlite.Storage.Internal.SqliteRelationalConnection.Open (System.Boolean errorsExpected) [0x00000] in <74192050a4d342039620dc7ef6678f71>:0
  at Microsoft.EntityFrameworkCore.Sqlite.Storage.Internal.SqliteDatabaseCreator.Exists () [0x0000c] in <74192050a4d342039620dc7ef6678f71>:0
  at Microsoft.EntityFrameworkCore.Migrations.HistoryRepository.Exists () [0x0000b] in <69f795dffc844780bfcfff4ff8415a92>:0
  at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate (System.String targetMigration) [0x00012] in <69f795dffc844780bfcfff4ff8415a92>:0
  at Microsoft.EntityFrameworkCore.RelationalDatabaseFacadeExtensions.Migrate (Microsoft.EntityFrameworkCore.Infrastructure.DatabaseFacade databaseFacade) [0x00010] in <69f795dffc844780bfcfff4ff8415a92>:0
  at TestEfCorePlusSqlite.Program.Main (System.String[] args) [0x0000e] in <c4fad569c9a241ef887b5b2ddbc0225f>:0

Since the application is built with Any CPU configuration, x86 and x64 folders are created in bin/Debug, both containing an e_sqlite3.dll. I already tried to copy the x86 dll to bin/Debug but the error still occurred.

What I've tried so far:

  • installing Microsoft.EntityFrameworkCore.Sqlite.Core together with SQLitePCLRaw.bundle_e_sqlite3 as suggested here
  • installing Microsoft.EntityFrameworkCore.Sqlite (or Microsoft.Data.Sqlite or SQLitePCLRaw.bundle_green) as suggested here
  • different combinations of SQLitePCLRaw.* packages

What do I have to do to get EF Core and SQlite running on Mono?

1
0
5/24/2019 9:42:20 AM

Accepted Answer

After a refreshing weekend I took another glance at the problem. I found the official Mono documentation regarding DllNotFoundException and used MONO_LOG_LEVEL=debug mono YourApp.exe to find out which lib Mono is trying to load. It was /usr/lib/libe_sqlite3.so which was not available on my system. All I did was to copy the available /usr/lib/libsqlite3.so and rename it to libe_sqlite3.so. I'm not sure if this is the preferred way but my application works.

0
5/27/2019 8:58:45 AM


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