How to Fix Unable to Load DLL ‘sni.dll’ or one of its dependencies ASP.NET Core

In previous post, we have explained few error that you can find when deploying ASP.NET Core. In this article, we will show about other error message that you can find when deploying your Asp.net core. For your information, this error message can happened in Asp.net core 1 until latest Asp.net core 7.

The following is full error message:

Unhandled exception. Unhandled exception. System.TypeInitializationException: The type initializer for ‘System.Data.SqlClient.TdsParser’ threw an exception.
—> System.TypeInitializationException: The type initializer for ‘System.Data.SqlClient.SNILoadHandle’ threw an exception.
—> System.DllNotFoundException: Unable to load DLL ‘sni.dll’ or one of its dependencies: The specified module could not be found. (0x8007007E)
at System.Data.SqlClient.SNINativeMethodWrapper.SNIInitialize(IntPtr pmo)
at System.Data.SqlClient.SNINativeMethodWrapper.SNIInitialize()
at System.Data.SqlClient.SNILoadHandle..ctor()
at System.Data.SqlClient.SNILoadHandle..cctor()
— End of inner exception stack trace —
at System.Data.SqlClient.TdsParser..cctor()
— End of inner exception stack trace —
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObject
sTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& co
nnection)
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, TaskCompletionSource`1 retry
, DbConnectionOptions userOptions, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionFactory.TryGetConnection(DbConnection owningConnection, TaskCompletionSource`
1 retry, DbConnectionOptions userOptions, DbConnectionInternal oldConnection, DbConnectionInternal& connection)
at System.Data.ProviderBase.DbConnectionInternal.TryOpenConnectionInternal(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionClosed.TryOpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory, TaskCompletionSource`1 retry, DbConnectionOptions userOptions) at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
at System.Data.SqlClient.SqlConnection.Open()
at Dapper.SqlMapper.QueryImpl[T](IDbConnection cnn, CommandDefinition command, Type effectiveType)+MoveNext() in C:\projects\dapper\Dapper\SqlMapper.cs:line 1079
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at Dapper.SqlMapper.Query[T](IDbConnection cnn, String sql, Object param, IDbTransaction transaction, Boolean buffered, Nullable`1 commandTimeout, Nullable`1 commandType) in C:\projects\dapper\Dapper\SqlMapper.cs:line 893

How to Solve it?

It turns out, that Dapper is missing a reference to System.Data.SqlClient. Adding the System.Data.SqlClient NuGet package to the project solves the issue:

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