MSSQL Error The underlying provider failed on Open

Question

I was using an  mdf for connecting to a database and entityClient  Now I want to change the connection string so that there will be no  mdf file   Is the following connectionString correct    lt connectionStrings gt      lt  -- lt add name  conString  connectionString  metadata res     conString csdl res     conString ssdl res     conString msl provider System Data SqlClient provider connection string  amp quot Data Source   SQL2008 AttachDbFilename  DataDirectory  NData mdf Integrated Security True Connect Timeout 30 User Instance True MultipleActiveResultSets True amp quot   providerName  System Data EntityClient    gt -- gt      lt add name  conString  connectionString  metadata res     conString csdl res     conString ssdl res     conString msl provider System Data SqlClient provider connection string  amp quot Data Source   SQL2008 Initial Catalog NData Integrated Security True Connect Timeout 30 User Instance True MultipleActiveResultSets True amp quot   providerName  System Data EntityClient    gt      Because I always get the error      The underlying provider failed on Open

User · Answer

You should see innerException to see what the inner cause of throwing of error is    In my case  the original error was      Unable to open the physical file  D  Projects2 xCU xCU App Data xCUData log ldf   Operating system error 5   5 Access is denied       An attempt to attach an auto-named database for file D  Projects2 xCU xCU App Data xCUData mdf failed  A database with the same name exists  or specified file cannot be opened  or it is located on UNC share    which solved by giving full permission to current user for accessing related mdf and ldf files using files  properties

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NONE of the answers worked for me  I think that some of us all make silly mistakes   there are 100 ways to fail      My issue was new project   I setup all the configuration in another project  but the caller was a Web Api project in which I had to copy the same connection string in the Web api project      I think this is crazy considering I was not even newing up dbcontext or anything from the web api     Otherwise the class library was trying to look for a Database named  TokenApi Core CalContext      of which my project is named   TokenApi Core and the CalContext is the name of the connection string and the file name

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This is common issue only  Even I have faced this issue  On the development machine  configured with Windows authentication  it is worked perfectly    lt add name  ShoppingCartAdminEntities  connectionString  metadata res     ShoppingCartAPIModel csdl res     ShoppingCartAPIModel ssdl res     ShoppingCartAPIModel msl provider System Data SqlClient provider connection string  amp quot data source   SQlExpress initial catalog ShoppingCartAdmin Integrated Security True multipleactiveresultsets True application name EntityFramework amp quot   providerName  System Data EntityClient    gt    Once hosted in IIS with the same configuration  I got this error      The underlying provider failed on Open   It was solved changing connectionString in the configuration file    lt add name  MyEntities  connectionString  metadata res     ShoppingCartAPIModel csdl res     ShoppingCartAPIModel ssdl res     ShoppingCartAPIModel msl provider System Data SqlClient provider connection string  amp quot data source MACHINE Name SQlExpress initial catalog ShoppingCartAdmin persist security info True user id sa password notmyrealpassword multipleactiveresultsets True application name EntityFramework amp quot   providerName  System Data EntityClient    gt    Other common mistakes could be    Database service could be stopped Data Source attributes pointing to a local database with Windows authentication and hosted in IIS Username and password could be wrong

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Defining a new Windows Firewall rule for SQL nbsp Server  and for port 1433  on the server machine solves this error  if your servername  user login name or password is not wrong in your connection string

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I got rid of this by resetting IIS  but still using Integrated Authentication in the connection string

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I had a similar problem  In my test-cases executions I always got this error  I found out  that my  Distributed Transaction Service  was not started  run  services msc -  start  Distributed Transaction Service   best to set it to start automatic    After I did that  it worked like a charm

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I had the same problem but what worked for me was removing this from the Connection String   persist security info True

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You could try to replace the metadata   metadata res    conString csdl res    conString ssdl res     conString msl  to   metadata res

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When you receive this exception  make sure to expand the detail and look at the inner exception details as it will provide details on why the login failed  In my case the connection string contained a user that did not have access to my database   Regardless of whether you use Integrated Security  the context of the logged in Windows User  or an individual SQL account  make sure that the user has proper access under  Security  for the database you are trying to access to prevent this issue

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I found the problem was that I had the server path within the connection string in one of these variants   SERVER SQLEXPRESS SERVER   When really I should have     SQLEXPRESS   For some reason I got the error whenever it had difficulty locating the instance of SQL

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If you happen to get this error on an ASP NET web application  in addition to other things mentioned check the following    Database User Security Permissions  which users are allowed access to your database  Check your application pool in IIS and make sure it s the correct one that is allowed access to your database

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Make sure that each element value in the connection string being supplied is correct  In my case  I was getting the same error because the name of the catalog  database name  specified in the connection string was incorrect

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context Connection Open   didn t help solving my problem so I tried enabling  Allow Remote Clients  in DTC config  no more error   In windows 7 you can open the DTC config by running dcomcnfg  Component Services -  Computers -  My Computer -  Distributed Transaction Coordinator -  Right click to Local DTC -  Security

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I was also facing the same issue  Now I have done it by removing the user name and password from the connection string

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I was searching all over the web for this problem  I had the wrong name in the connection string  please check you connection string in web config  I had name  AppTest  but it should have been name  App    In my AppTestContext cs file I had   public AppTestContext     this  App         Wrong connection string    lt add connectionString  Data Source 127 0 0 1 Initial Catalog AppTest Integrated Security SSPI MultipleActiveResultSets True  name  AppTest  providerName  System Data SqlClient    gt    Right connection string    lt add connectionString  Data Source 127 0 0 1 Initial Catalog AppTest Integrated Security SSPI MultipleActiveResultSets True  name  App  providerName  System Data SqlClient    gt

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The SQL Server Express service were not set tostart automatically    1  Go to control panel 2  Administrative Tools 3  Service 4  Set SQL Server express to start automatically by clicking on it 5  Right click and start the service  I hope that will help

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For me it was just a simple mistake   I used Amazon EC2  and I used my elastic IP address in the connection string  but when I changed IP addresses I forgot to update my connection string

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I have solved this way      Step 1    Open Internet Information Service Manager   Step 2  Click on Application Pools in left navigation tree   Step 3  Select your version Pool  In my case  I am using ASP  Net v4 0  If you dont have this version  select DefaultAppPool   Step 4  Right click on step 3  and select advanced settings   Step 5  Select Identity in properties window and click the button to change the value   Step 6  Select Local System in Built-in accounts combo box and click ok  That s it  Now run your application  Everything works well   Codeproject Solution   the-underlying-provider-failed-on-open

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I had the same issue few days ago  using  Integrated Security True   in the connection string you need to run the application pool identity under  localsystem  Sure this is not recommended but for testing it does the job   This is how you can change the identity in IIS 7  http   www iis net learn manage configuring-security application-pool-identities

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This can also happen if you restore a database and the user already exists with different schema  leaving you unable to assign the correct permissions    To correct this run   USE your database EXEC sp change users login  Auto Fix    user   NULL   cf  GO EXEC sp change users login  update one    user    user  GO

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I had this error and found a few solutions   Looking at your connection string  it looks valid   I found this blog post  the problem here is that they were using Integrated Security   If you are running on IIS  your IIS user needs access to the database   If you are using Entity Framework with Transactions  Entity Framework automatically opens and closes a connection with each database call   So when using transactions  you are attempting to spread a transaction out over multiple connections   This elevates to MSDTC    See this reference for more information    Changing my code to the following fixed it   using  DatabaseEntities context   new DatabaseEntities          context Connection Open           the rest

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I had a similar issue with the SQL Server Express Edition on Windows Server 2003  I simply added the network service as a user in the database security

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I had this error suddenly happen out of the blue on one of our sites  In my case  it turned out that the SQL user s password had expired  Unticking the password expiration box in SQL Server Management Studio did the trick

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I had a similar error with the inner exception as below      operation is not valid for the state of the transaction   I could resolve it by enabling DTC security settings   Go To Properties of DTC  under Security Tab  check the below   Network DTC Access Allow RemoteClients Transaction Manager Communication Allow Inbound Allow Outbound

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A common mistake that I did because I was moving application from once pc to another and none of the above worked was that I forgot to copy the connection string to both App Config and Web Config

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I posted a similar issue here  working with a SQL 2012 db hosted on Amazon RDS  The problem was in the connection string - I had  Application Name  and  App  properties in there  Once I removed those  it worked   Entity Framework 5 and Amazon RDS -  quot The underlying provider failed on Open  quot

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In my case I had a mismatch between the connection string name I was registering in the context s constructor vs the name in my web config  Simple mistake caused by copy and paste  D      public DataContext             base nameOrConnectionString   ConnStringName                 Database SetInitializer lt DataContext gt  null

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I had this problem because the Application Pool login this app was running under had changed   In IIS    Find the Application pool by clicking on your site and going to Basic Settings  Go to Application Pools  Click on your site s application pool  Click on Advanced Settings  In Identity  enter account login and password  Restart your site and try again

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I had a similar issue with exceptions due to the connection state  then I realized I had my domain service class variable marked as static  by mistake      My guess is that once the service library is loaded into memory  each new call ends up using the same static variable value  domain service instance   causing conflicts via the connection state    I think also that each client call resulted in a new thread  so multiple threads accessing the same domain service instance equated to a train wreck

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In IIS set the App Pool Identity As Service Account user or Administrator Account or ant account which has permission to do the operation on that DataBase

[c#] MSSQL Error 'The underlying provider failed on Open'

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