Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding. The statement has been terminated

I have many users on my web site (20000-60000 per day), which is a download site for mobile files. I have remote access to my server (windows server 2008-R2).
I’ve received “Server is unavailable” errors before, but am now seeing a connection timeout error.

I’m not familiar with this – why does it occur and how can I fix it?

The full error is below:

Server Error in ‘/’ Application. Timeout expired. The timeout period
elapsed prior to completion of the operation or the server is not
responding. The statement has been terminated. Description: An
unhandled exception occurred during the execution of the current web
request. Please review the stack trace for more information about the
error and where it originated in the code.

Exception Details: System.Data.SqlClient.SqlException: Timeout
expired. The timeout period elapsed prior to completion of the
operation or the server is not responding. The statement has been

Source Error:

An unhandled exception was generated during the execution of the
current web request. Information regarding the origin and location of
the exception can be identified using the exception stack trace below.

Stack Trace:
[SqlException (0x80131904): Timeout expired. The timeout period
elapsed prior to completion of the operation or the server is not
responding. The statement has been terminated.]
System.Data.SqlClient.SqlConnection.OnError(SqlException exception,
Boolean breakConnection) +404
System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning() +412
System.Data.SqlClient.TdsParser.Run(RunBehavior runBehavior,
SqlCommand cmdHandler, SqlDataReader dataStream,
BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject
stateObj) +1363
System.Data.SqlClient.SqlCommand.FinishExecuteReader(SqlDataReader ds,
RunBehavior runBehavior, String resetOptionsString) +6387741
cmdBehavior, RunBehavior runBehavior, Boolean returnStream, Boolean
async) +6389442
cmdBehavior, RunBehavior runBehavior, Boolean returnStream, String
method, DbAsyncResult result) +538
result, String methodName, Boolean sendToPipe) +689
System.Data.SqlClient.SqlCommand.ExecuteNonQuery() +327
NovinMedia.Data.DbObject.RunProcedure(String storedProcName,
IDataParameter[] parameters, Int32& rowsAffected) +209
DataLayer.OnlineUsers.Update_SessionEnd_And_Online(Object Session_End,
Boolean Online) +440
NiceFileExplorer.Global.Application_Start(Object sender, EventArgs e)
[HttpException (0x80004005): Timeout expired. The timeout period
elapsed prior to completion of the operation or the server is not
responding. The statement has been terminated.]
context, HttpApplication app) +4052053
appContext, HttpContext context, MethodInfo[] handlers) +191
System.Web.HttpApplication.InitSpecial(HttpApplicationState state,
MethodInfo[] handlers, IntPtr appContext, HttpContext context) +352
appContext, HttpContext context) +407
appContext) +375
[HttpException (0x80004005): Timeout expired. The timeout period
elapsed prior to completion of the operation or the server is not
responding. The statement has been terminated.]
System.Web.HttpRuntime.FirstRequestInit(HttpContext context) +11686928
System.Web.HttpRuntime.EnsureFirstRequestInit(HttpContext context)
+141 System.Web.HttpRuntime.ProcessRequestNotificationPrivate(IIS7WorkerRequest
wr, HttpContext context) +4863749

my Application_Start in Global.asax is like below:

protected void Application_Start(object sender, EventArgs e)
    Application["OnlineUsers"] = 0;


    AddTask("DoStuff", 10);

The stored procedure being called is:

ALTER Procedure [dbo].[sp_OnlineUsers_Update_SessionEnd_And_Online]
    @Session_End datetime,
    @Online bit
    Update OnlineUsers
        [Session_End] = @Session_End,
        [Online] = @Online


I have two methods for getting online users:

  1. using Application["OnlineUsers"] = 0;
  2. the other one using database

So, for method #2 I reset all OnlineUsers at Application_Start. There are over 482,751 records in that table.


Thank you for visiting the Q&A section on Magenaut. Please note that all the answers may not help you solve the issue immediately. So please treat them as advisements. If you found the post helpful (or not), leave a comment & I’ll get back to you as soon as possible.

Method 1

Looks like you have a query that is taking longer than it should.
From your stack trace and your code you should be able to determine exactly what query that is.

This type of timeout can have three causes;

  1. There’s a deadlock somewhere
  2. The database’s statistics and/or query plan cache are incorrect
  3. The query is too complex and needs to be tuned

A deadlock can be difficult to fix, but it’s easy to determine whether that is the case. Connect to your database with Sql Server Management Studio. In the left pane right-click on the server node and select Activity Monitor. Take a look at the running processes.
Normally most will be idle or running. When the problem occurs you can identify any blocked process by the process state. If you right-click on the process and select details it’ll show you the last query executed by the process.

The second issue will cause the database to use a sub-optimal query plan. It can be resolved by clearing the statistics:

exec sp_updatestats

If that doesn’t work you could also try

dbcc freeproccache

You should not do this when your server is under heavy load because it will temporarily incur a big performace hit as all stored procs and queries are recompiled when first executed.
However, since you state the issue occurs sometimes, and the stack trace indicates your application is starting up, I think you’re running a query that is only run on occasionally. You may be better off by forcing SQL Server not to reuse a previous query plan. See this answer for details on how to do that.

I’ve already touched on the third issue, but you can easily determine whether the query needs tuning by executing the query manually, for example using Sql Server Management Studio. If the query takes too long to complete, even after resetting the statistics you’ll probably need to tune it. For help with that, you should post the exact query in a new question.

Method 2

In your code where you run the stored procedure you should have something like this:

SqlCommand c = new SqlCommand(...)

Add such a line of code:

c.CommandTimeout = 0;

This will wait as much time as needed for the operation to complete.

Method 3

You could set the CommandTimeout property of the SQL Command to allow for the long running SQL transaction.

You might also need to look at the SQL Query that is causing the timeout.

Method 4

Maybe it will be useful for somebody.
I faced with the same problem and in my case the reason was the SqlConnection was opened and not disposed in the method that I called in loop with about 2500 iterations. Connection pool was exhausted. Proper disposing solved the problem.

Method 5

I had the same issue and resolved by adding “Connection Time” value in web.config file. locate the connectionStrings and add Connection Timeout=3600″

here is the sample

    <add name="MyConn" providerName="System.Data.SqlClient" connectionString="Data Source=MySQLServer;Initial Catalog=MyDB;User ID=sa;Password=123;Connection Timeout=3600" />

Method 6

While all the earlier responses address the issue they did not cover all cases.

Microsoft has acknowledged the issue and fixed it in 2011 for supported operating systems, so if you get the stack trace like:

Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.
at System.Data.SqlClient.SqlInternalConnection.OnError(SqlException exception, Boolean breakConnection)
at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning()
at System.Data.SqlClient.TdsParserStateObject.ReadSniError(TdsParserStateObject stateObj, UInt32 error)
at System.Data.SqlClient.TdsParserStateObject.ReadSni(DbAsyncResult asyncResult, TdsParserStateObject stateObj)

you may need to update your .NET assemblies.

This issue occurs because of an error in the connection-retry
algorithm for mirrored databases.

When the retry-algorithm is used, the data provider waits for the
first read (SniReadSync) call to finish. The call is sent to the
back-end computer that is running SQL Server, and the waiting time is
calculated by multiplying the connection time-out value by 0.08.
However, the data provider incorrectly sets a connection to a doomed
state if a response is slow and if the first SniReadSync call is not
completed before the waiting time expires.

See KB 2605597 for details


Method 7

You have to set CommandTimeout attribute. You can set the CommandTimeout attribute in DbContext child class.

public partial class StudentDatabaseEntities : DbContext
    public StudentDatabaseEntities()
        : base("name=StudentDatabaseEntities")
        this.Database.CommandTimeout = 180;

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
        throw new UnintentionalCodeFirstException();

    public virtual DbSet<StudentDbTable> StudentDbTables { get; set; }

Method 8

I faced same problem worked on it around 3 days. I noticed as our number of records are not much our senior developer keeps 2 images and Fingerprint in database. When I try to fetch this hex values it taking long time, I calculate average time to execute my procedure its around 38 seconds. The default commandtimeout is 30 seconds so its less than average time required to run my stored procedure. I set my commandtimeout like below

cmd.CommandTimeout = 50

and its working fine but sometimes if your query takes more than 50 seconds it will prompt same error.

Method 9

If you are using ASP.NET Core with the Startup.cs convention, you can access and set the query command timeout option like this:

public void ConfigureServices(IServiceCollection services)
    services.AddDbContextPool<MyDbContext>(_ =>
        _.UseSqlServer(Configuration.GetConnectionString("MyConnectionString"), options => 
            options.CommandTimeout(180); // 3 minutes

Method 10

I encountered this error recently and after some brief investigation, found the cause to be that we were running out of space on the disk holding the database (less than 1GB).

As soon as I moved out the database files (.mdf and .ldf) to another disk on the same server (with lots more space), the same page (running the query) that had timed-out loaded within three seconds.

One other thing to investigate, while trying to resolve this error, is the size of the database log files. Your log files just might need to be shrunk.

Method 11

Default timeout is 15 seconds, to change that, 0 is unlimited, any other number is the number of seconds.

In Code

using (SqlCommand sqlCmd = new SqlCommand(sqlQueryString, sqlConnection))
      sqlCmd.CommandTimeout = 0; // 0 = give it as much time as it needs to complete

In Your Web.Config, “Command Timeout=0;” do not time out, or as below 1 hour (3600 seconds)

  <add name="ConnectionString" connectionString="Data Source=ServerName;User ID=UserName;Password=Password;Command Timeout=3600;" providerName="System.Data.SqlClient" />

Method 12

I have issue with large calculation in sp_foo that take large time so i fixed
with this little bit code

public partial class FooEntities : DbContext
   public FooEntities()
         : base("name=FooEntities")
        this.Configuration.LazyLoadingEnabled = false;

        // Get the ObjectContext related to this DbContext
        var objectContext = (this as IObjectContextAdapter).ObjectContext;

        // Sets the command timeout for all the commands
        objectContext.CommandTimeout = 380;

Method 13

@SilverLight.. This is clearly an issue with a Database object. It can be a badly written query, or missing indexes. But as of now I won’t suggest you to increase the timeout without investigating the issue with your Database objects

NovinMedia.Data.DbObject.RunProcedure(String storedProcName, IDataParameter[] parameters, Int32& rowsAffected) +209

Put a breakpoint on this line of code to findout the procedure name and then optimise the procedure by looking at its execution plan.

I cannot help you more till the time you post details about the stored procedure.

Method 14


EXEC SP_CONFIGURE 'remote query timeout', 1800
EXEC sp_configure

EXEC SP_CONFIGURE 'show advanced options', 1
EXEC sp_configure

EXEC SP_CONFIGURE 'remote query timeout', 1800
EXEC sp_configure

rebuild your index

Method 15


  1. Rebooting both application and DB servers is the quickest fix where data volume, network settings and code haven’t changed. We always do so as a rule
  2. May be indicator of failing hard-drive that needs replacement – check system notifications

I have often encountered this error for various reasons and have had various solutions, including:

  1. refactoring my code to use SqlBulkCopy
  2. increasing Timeout values, as stated in various answers or checking for
    underlying causes (may not be data related)
  3. Connection Timeout (Default 15s) – How long it takes to wait for a connection to be established with the SQL server before terminating – TCP/PORT related – can go through a troubleshooting checklist (very handy MSDN article)
  4. Command Timeout (Default 30s) – How long it takes to wait for the execution of a query – Query execution/network traffic related – also has a troubleshooting process (another very handy MSDN article)
  5. Rebooting of the server(s) – both application & DB Server (if separate) – where code and data haven’t changed, environment must have changed – First thing you must do. Typically caused by patches (operating system, .Net Framework or SQL Server patches or updates). Particularly if timeout exception appears as below (even if we do not use Azure):
    • System.Data.Entity.Core.EntityException: An exception has been raised that is likely due to a transient failure. If you are connecting to a SQL Azure database consider using SqlAzureExecutionStrategy. —> System.Data.Entity.Core.EntityCommandExecutionException: An error occurred while executing the command definition. See the inner exception for details. —> System.Data.SqlClient.SqlException: A transport-level error has occurred when receiving results from the server. (provider: TCP Provider, error: 0 – The semaphore timeout period has expired.) —> System.ComponentModel.Win32Exception: The semaphore timeout period has expired

Method 16

Also make sure you just don’t have a pending transaction. 🙂

I was doing some tests around and began a transaction to be safe but never closed it. I wish the error would have been more explicit but oh well!

Method 17

We recently upgraded to the NuGet version of SqlClient (Microsoft.Data.SqlClient) which contains a bug. This bug was introduced during the lifetime of the 1.x cycle and has already been fixed. The fix will be available in the 2.0.0 release which is not available at the time of this writing. A preview is available.

You can inspect the details here:

Method 18

I had this problem once and in my case was an uncommited transaction in SQL. After I commited, the problem went away.

Method 19

Timeout expired because the sql query is taking more time than you set
in sqlCommand.CommandTimeout property.

Obviously you can increase CommandTimeout to solve this issue but
before doing that you must optimize your query by adding index. If you
run your query in Sql server management studio including actual
execution plan
then Sql server management studio will suggest
you proper index. Most of the case you will get rid of timeout issue
if you can optimize your query.

Method 20

We’ve had hard times on Timeout expired/max pool reached Sqlexception. As a workarround and to prevent restarting the server or the service we modify the MAX SERVER MEMORY variable in SQL Server (either through SQL Managment Studio or T-SQL):

DECLARE @maxMem INT = 3000 --Max. memory for SQL Server instance in MB
EXEC sp_configure 'show advanced options', 1

This temporarily fixes the issue until it happens again. In our case we suspect that it has to do with connection leaks at app level.

Method 21

Also you need to check if individual record is not getting updated in the logic because with update trigger in the place causes time out error too.

So, the solution is to make sure you perform bulk update after the loop/cursor instead of one record at a time in the loop.

Method 22

I had this problem and it went away when I moved from ADO.Net to Dapper for my queries.

Method 23

As others have said, the problem might be related with a pending transaction.
In my case I had to send the DbTransaction variable as a parameter in the ExecuteScalar method for the procedure to be executed properly.




ExecuteScalar(command, transaction)

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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