SQL Server Express 연결 오류 - A network-related or instance-specific error occurred while establishing a connection to SQL Server.
희한한 일이군요. SQL Server Express에 접근하는 데 SqlConnection의 경우 다음과 같은 예외가 발생합니다.
Unhandled Exception: System.Data.SqlClient.SqlException: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
at System.Data.SqlClient.TdsParser.Connect(ServerInfo serverInfo, SqlInternalConnectionTds connHandler, Boolean ignoreSniOpenTimeout, Int64 timerExpire, Boolean encrypt, Boolean trustServerCert, Boolean integratedSecurity, Boolean withFailover)
at System.Data.SqlClient.SqlInternalConnectionTds.AttemptOneLogin(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean ignoreSniOpenTimeout, TimeoutTimer timeout, Boolean withFailover)
at System.Data.SqlClient.SqlInternalConnectionTds.LoginNoFailover(ServerInfo serverInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString connectionOptions, SqlCredential credential, TimeoutTimer timeout)
at System.Data.SqlClient.SqlInternalConnectionTds.OpenLoginEnlist(TimeoutTimer timeout, SqlConnectionString connectionOptions, SqlCredential credential, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance)
at System.Data.SqlClient.SqlInternalConnectionTds..ctor(DbConnectionPoolIdentity identity, SqlConnectionString connectionOptions, SqlCredential credential, Object providerInfo, String newPassword, SecureString newSecurePassword, Boolean redirectedUserInstance, SqlConnectionString userConnectionOptions, SessionData reconnectSessionData)
at System.Data.SqlClient.SqlConnectionFactory.CreateConnection(DbConnectionOptions options, DbConnectionPoolKey poolKey, Object poolGroupProviderInfo, DbConnectionPool pool, DbConnection owningConnection, DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionFactory.CreatePooledConnection(DbConnectionPool pool, DbConnection owningObject, DbConnectionOptions options, DbConnectionPoolKey poolKey, DbConnectionOptions userOptions)
at System.Data.ProviderBase.DbConnectionPool.CreateObject(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
at System.Data.ProviderBase.DbConnectionPool.UserCreateRequest(DbConnection owningObject, DbConnectionOptions userOptions, DbConnectionInternal oldConnection)
at System.Data.ProviderBase.DbConnectionPool.TryGetConnection(DbConnection owningObject, UInt32 waitForMultipleObjectsTimeout, Boolean allowCreate, Boolean onlyOneCheckConnection, DbConnectionOptions userOptions, DbConnectionInternal& connection)
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.SqlClient.SqlConnection.TryOpenInner(TaskCompletionSource`1 retry)
at System.Data.SqlClient.SqlConnection.TryOpen(TaskCompletionSource`1 retry)
at System.Data.SqlClient.SqlConnection.Open()
at ConsoleApp1.Program.Main(String[] args) in C:\test\ConsoleApp1\ConsoleApp1\Program.cs:line 16
.udl 파일로 테스트 해도 역시 이런 식의 오류 2개가 이어서 나옵니다.
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Microsoft Data Link Error
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[DBNETLIB][ConnectionOpen (Connect()).]SQL Server does not exist or access denied.
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Microsoft Data Link
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Login failed. Catalog information cannot be retrieved.
재미있는 것은, 제가 가진 다음과 같은 테스트 PC마다 컴퓨터명으로 할 때와 IP로 할 때 연결 유무가 다르다는 점입니다.
[Use Windows NT Integrated security]
testdb\SQLEXPRESS 192.168.0.5\SQLEXPRESS
win2003x86 OK FAIL
win2003x64 FAIL FAIL
win2008x86 FAIL FAIL
win2008r2 FAIL FAIL
win2012 OK FAIL
win2016 OK FAIL
[Use a specific user name and password]
testdb\SQLEXPRESS 192.168.0.5\SQLEXPRESS
clean 2008r2 OK FAIL
clean 2012 FAIL OK
현상으로 봐서는 다음의 내용과는 다소 다르지만,
원격에서 SQL 서버는 연결되지만, SQL Express는 연결되지 않는 경우
; https://www.sysnet.pe.kr/2/0/2908
그래도 해결책은 이번에도 역시나 "SQL Server Browser" 서비스가 stopped였기 때문에 발생한 것이었습니다. 아예 모든 머신에서 접속이 안되었으면 바로 해결을 했겠지만 표로 정리한 내용처럼 일부는 되는 현상 때문에 생각지도 않은 ^^; 결과였습니다.
이번엔 일단 이 정도로 끝나고 다음번에 시간 나면 한번 분석을 해봐야겠습니다. ^^
[이 글에 대해서 여러분들과 의견을 공유하고 싶습니다. 틀리거나 미흡한 부분 또는 의문 사항이 있으시면 언제든 댓글 남겨주십시오.]