I am getting this error:
Timeout expired. The timeout period elapsed prior to completion of the operation or the server is not responding.
I know there are already guides out there to help solve this but they are not working for me. What am I missing or where should I add the code to these SQL statements in my C# program:
String sql = project1.Properties.Resources.myQueryData;
SqlDataAdapter sqlClearQuestDefects = new SqlDataAdapter(sql,
"Data Source=ab;Initial Catalog=ac;User ID=ad; Password =aa");
DataSet lPlanViewData = new DataSet();
sqlClearQuestDefects.Fill(lPlanViewData, "PlanViewData");
I am getting the timeout error at this line:
SqlDataAdapter sqlClearQuestDefects = new SqlDataAdapter(sql,
"Data Source=ab;Initial Catalog=ac;User ID=ad; Password =aa");
SqlDataAdapter adp = new SqlDataAdapter();
adp.SelectCommand.CommandTimeout = 0; // Set the Time out on the Command Object
You're trying to connect to a SQL Server, and it is taking longer than ADO.NET is willing to wait.
Try connecting to the same server, using the same username and password, using SQL Server Management Studio. If you get the same error, there is either something wrong with your connection string, the server you specify is not running, or you can't get to the server across the network from where you are (maybe you're on a public IP address trying to get in to an internal server name). I can't think of a scenario in which you'd enter the exact same server and credentials into SSMS and connect, then do the same in ADO.NET and fail.
If you're on a slow network, you can try increasing the timeout value. However, if a connection is going to happen at all, it should happen pretty quickly.
Take a look at both your SQL Native Client settings, and the SQL Server settings on the server. There is a section for allowed protocols; SQL can connect using a variety of protocols. Usually, you want TCP/IP for a server on the network, and Named Pipes for a server running on your own computer.
EDIT FROM YOUR COMMENT: Oh, that's normal; happens all the time. From time to time on a TCP network, packets "collide", or are "lost" in transmission. It's a known weakness of packet-switching technologies, which is managed by the TCP protocol itself in most cases. One case in which it isn't easily detected is when the initial request for a connection is lost in the shuffle. In that case, the server doesn't know there was a request, and the client didn't know their request wasn't received. So, all the client can do is give up.
To make your program more robust, all you have to do is expect a failure or two, and simply re-try your request. Here's a basic algorithm to do that:
SqlDataAdapter sqlClearQuestDefects;
short retries = 0;
while(true)
{
try
{
sqlClearQuestDefects = new SqlDataAdapter(sql, "Data Source=ab;Initial Catalog=ac;User ID=ad; Password =aa");
break;
}
catch(Exception)
{
retries++;
//will try a total of three times before giving up
if(retries >2) throw;
}
}
Since the exact command to increase connection time out wasn't mentioned in the other answers (of yet)- if you do determine a need to increase your connection time out, you would do so in your connection string as follows:
Data Source=ab;Initial Catalog=ac;User ID=ad; Password =aa; Connection Timeout=120
Where 120 = 120 seconds. Default is 20 or 30 as I recall.
This is probably a connection issue with your database, for example if you had the following connection string:
"Data Source=MyDatabaseServer...
Then you need to make sure that:
The machine MyDatabaseServer is connected to the network and is accessible from the machine you are running your application from (under the name "MyDatabaseServer")
The database server is running on MyDatabaseServer
The database server on MyDatabaseServer is configured to accept connections from remote machines
The firewall settings both on the local machine and MyDatabaseServer are correctly set up to allow SQL Server connections through
Your username / password etc... are correct
You can also try connecting to the given database instance using SQL Server Management Studio from the client machine as a diagnosis step.
There are plenty of articles that address SQL Server connectivity issues - do a Google search for the specific error message that comes up or failing that as a specific question on Server Fault
Faced this problem recently and found the resolution that worked for me.
By the way, setting Timeout = 0 helped to avoid the exception, but the execution time was unreasonable, while manual execution of the store procedure took a few seconds.
Bottom line:
I added SET IMPLICIT_TRANSACTIONS OFF to the stored procedure that is used to fill the data set.
From MSDN:
The SQL Server Native Client OLE DB Provider for SQL Server and the
SQL Server Native Client ODBC driver automatically set
IMPLICIT_TRANSACTIONS to OFF when connecting. SET
IMPLICIT_TRANSACTIONS defaults to OFF for connections with the
SQLClient managed provider, and for SOAP requests received through
HTTP endpoints.
[...]
When SET ANSI_DEFAULTS is ON, SET IMPLICIT_TRANSACTIONS is ON.
So I believe that in my case defaults weren't as required. (I couldn't check that. Don't have enough privileges on SQL server). But adding this line to my SP solved the problem.
IMPORTANT: In my case I didn't need the transaction, so I had no problem to cancel the implicit transaction setting. If in your case transaction is a must you, probably, shouldn't use this solution.
Related
I am working on a project where a thread is run and opens a permanent database connection. The reason for this, is potentially as the project grows it could receive more and more requests so it's more efficient to keep the database open and usable instead of opening and closing the database.
Basically what the thread does is look for events in a queue, and if there is an event it starts working on the database to store and process the event. At its peak this thread could receive 50,000-100,000 requests a day potentially a lot more, as more and more users (hopefully) use the service.
However, because it's new, there are times where this thread doesn't have anything to do, so I end up hitting the exception "The connection must be valid and open" and I believe this is because the connection to the database is automatically dropped over 8 hours of inactivity. At the moment this can happen so I am trying to add a Keepalive option to the connection so this doesn't happen but for some reason, as soon as I add this, I then get the error "Unable to connect to any of the specified MySQL hosts".
I am using a MysqlConnectionStringBuilder as follows:
MySqlConnectionStringBuilder connectionBuilder = new MySqlConnectionStringBuilder();
connectionBuilder.Server = server;
connectionBuilder.UserID = username;
connectionBuilder.Password = password;
connectionBuilder.Port = 3306;
//Open the connection
MySqlConnection conn = new MySqlConnection(connectionBuilder.ConnectionString);
conn.Open();
This above works perfectly fine until I add the following:
connectionBuilder.Keepalive = 60;
When the above line is added is when I then get the error.
I am using a TCP connection as it's a remote connection from my Dev PC to a dev server - is there a setting on the server to enable this? as everything I've found on Google this option is all that's required.
I have an API server that interacts with an Azure-hosted PostgreSQL database instance. There are a large number (>50) of postgres databases on that one postgres server. Any given API request may have to interact with any given database.
Unfortunately, our Azure plan for Postgres only allows 50 connections. I regularly have requests fail because Postgres won't accept more. My ADO.NET connection pool is still holding onto database connections for recently used databases, while connections to other databases error out.
I've tried setting the Max Pool Size on my connection strings, but it appears that the connection pool limit is applied per database, not per server. I still need as much pooling as I can get, opening new connections can take >1500ms, which is beyond my SLA if it happens on every request.
Is there a way to ask .NET to never open more than 50 database connections, either per server or total?
Set Max Pool Size and instead of connecting to a separate database connect to the same database on the server and then execute the \connect statement to change to the desired database. The following code fragment demonstrates creating an initial connection to the master database and then switching to the desired database specified in the databaseName string variable.
// Assumes that command is a NpgsqlCommand object and that
// connectionString connects to master.
command.Text = "\connect DatabaseName";
using (NpgsqlConnection connection = new NpgsqlConnection(
connectionString))
{
connection.Open();
command.ExecuteNonQuery();
}
I getting below error on trying to connect with the database :
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: Named
Pipes Provider, error: 40 - Could not open a connection to SQL Server)
Now sometimes i get this error and sometimes i dont so for eg:When i run my program for the first time,it open connection successfully and when i run for the second time i get this error and the next moment when i run my program again then i dont get error.
When i try to connect to same database server through SSMS then i am able to connect successfully but i am getting this network issue in my program only.
Database is not in my LOCAL.Its on AZURE.
I dont get this error with my local database.
Code :
public class AddOperation
{
public void Start()
{
using (var processor = new MyProcessor())
{
for (int i = 0; i < 2; i++)
{
if(i==0)
{
var connection = new SqlConnection("Connection string 1");
processor.Process(connection);
}
else
{
var connection = new SqlConnection("Connection string 2");
processor.Process(connection);
}
}
}
}
}
public class MyProcessor : IDisposable
{
public void Process(DbConnection cn)
{
using (var cmd = cn.CreateCommand())
{
cmd.CommandText = "query";
cmd.CommandTimeout = 1800;
cn.Open();//Sometimes work sometimes dont
using (var reader = cmd.ExecuteReader(CommandBehavior.CloseConnection))
{
//code
}
}
}
}
So i am confused with 2 things :
1) ConnectionTimeout : Whether i should increase connectiontimeout and will this solve my unusual connection problem ?
2) Retry Attempt Policy : Should i implement retry connection mechanism like below :
public static void OpenConnection(DbConnection cn, int maxAttempts = 1)
{
int attempts = 0;
while (true)
{
try
{
cn.Open();
return;
}
catch
{
attempts++;
if (attempts >= maxAttempts) throw;
}
}
}
I am confused with this 2 above options.
Can anybody please suggest me what would be the better way to deal with this problem?
Use a new version of .NET (4.6.1 or later) and then take advantage of the built-in resiliency features:
ConnectRetryCount, ConnectRetryInterval and Connection Timeout.
See the for more info: https://learn.microsoft.com/en-us/azure/sql-database/sql-database-connectivity-issues#net-sqlconnection-parameters-for-connection-retry
All applications that communicate with remote service are sensitive to transient faults.
As mentioned in other answers, if your client program connects to SQL Database by using the .NET Framework class System.Data.SqlClient.SqlConnection, use .NET 4.6.1 or later (or .NET Core) so that you can use its connection retry feature.
When you build the connection string for your SqlConnection object, coordinate the values among the following parameters:
ConnectRetryCount: Default is 1. Range is 0 through 255.
ConnectRetryInterval: Default is 1 second. Range is 1 through 60.
Connection Timeout: Default is 15 seconds. Range is 0 through 2147483647.
Specifically, your chosen values should make the following equality true:
Connection Timeout = ConnectRetryCount * ConnectionRetryInterval
Now, Coming to option 2, when you app has custom retry logic, it will increase total retry times - for each custom retry it will try for ConnectRetryCount times. e.g. if ConnectRetryCount = 3 and custom retry = 5, it will attempt 15 tries. You might not need that many retries.
If you only consider custom retry vs Connection Timeout:
Connection Timeout occurs usually due to lossy network - network with higher packet losses (e.g. cellular or weak WiFi) or high traffic load. It's up to you choose best strategy of using among them.
Below guidelines would be helpful to troubleshoot transient errors:
https://learn.microsoft.com/en-us/azure/sql-database/sql-database-connectivity-issues
https://learn.microsoft.com/en-in/azure/architecture/best-practices/transient-faults
As you can read here a retry logic is recommended even for a SQL Server installed on an Azure VM (IaaS).
FAULT HANDLING: Your application code includes retry logic and
transient fault handling? Including proper retry logic and transient
fault handling remediation in the code should be a universal best
practice, both on-premises and in the cloud, either IaaS or PaaS. If
this characteristic is missing, application problems may raise on both
Azure SQLDB and SQL Server in Azure VM, but in this scenario the
latter is recommended over the former.
An incremental retry logic is recommended.
There are two basic approaches to instantiating the objects from the application block that your application requires. In the first approach, you can explicitly instantiate all the objects in code, as shown in the following code snippet:
var retryStrategy = new Incremental(5, TimeSpan.FromSeconds(1),
TimeSpan.FromSeconds(2));
var retryPolicy =
new RetryPolicy<SqlDatabaseTransientErrorDetectionStrategy>(retryStrategy);
In the second approach, you can instantiate and configure the objects from configuration data as shown in the following code snippet:
// Load policies from the configuration file.
// SystemConfigurationSource is defined in
// Microsoft.Practices.EnterpriseLibrary.Common.
using (var config = new SystemConfigurationSource())
{
var settings = RetryPolicyConfigurationSettings.GetRetryPolicySettings(config);
// Initialize the RetryPolicyFactory with a RetryManager built from the
// settings in the configuration file.
RetryPolicyFactory.SetRetryManager(settings.BuildRetryManager());
var retryPolicy = RetryPolicyFactory.GetRetryPolicy
<SqlDatabaseTransientErrorDetectionStrategy>("Incremental Retry Strategy");
...
// Use the policy to handle the retries of an operation.
}
For more information, please visit this documentation.
Consider using Polly.
You could use a simple piece of code like -
RetryPolicy retryPolicy = Policy.Handle<Exception>()
.WaitAndRetry(3, retryAttempt =>
TimeSpan.FromSeconds(retryAttempt));
var result = retryPolicy.Execute(() => someClass.DoSomething());
This will retry the request up to three times.
It is completely possible that a connection can drop. "Fallacies of Distributed Computing" :).
It could be network connectivity issue. Could be at any end.
I would recommend: (assuming firewall is enabled for your machine on Azure)
Ping the server and see if there is any loss.
ping (server).database.windows.net
tracert
telnet can also be your friend.
The above three should help you to pin-point where the problem is.
I think your retry logic is fine.
Regarding you question
Increase Timeout
Only if you are sure that your query will take long time. If for a simple insert you have to increase timeout problem could be network connectivity.
Retry Logic
As already posted, it's now part of framework which you can utilise or the one you created should be fine. Ideally, it's good to have retry logic, even if you are sure about connectivity and speed. Just in case :)
You should increase the timeout because the time taken to establish a connection to a SQL server has many steps, hence it takes some time when it goes for establishing the connection for the first time. After establishment of the connection, the connection is pooled in the memory for re-use in subsequent queries.
Please refer below link for more detailed understanding on connection-pooling:
https://learn.microsoft.com/en-us/dotnet/framework/data/adonet/sql-server-connection-pooling
As you mentioned that this error generates sometimes, and not always, so there might be some network and connectivity factors for that. The default timeout for SQL connection is 15 seconds. I think if you change it to 30 seconds, it should work.
Are you using SQL Express or Workgroup Edition? If so, it's possible that the server is too busy to respond.
To rule out network problems, from a command prompt, do a PING -t SqlServername. Does every ping come back, or are some lost? This can be an indicator of network interruptions that might also cause this error, like a faulty switch. If they are all lost then (given that your database connection sometimes works) it is likely that ping is being blocked by a firewall somewhere: it may help diagnosis if you find that block and temporarily unblock it.
The error message indicates that you are using Named pipes. Are you using Named pipes on purpose? For most scenarios (including Azure database) I'd suggest enabling TCP/IP and disabling Named Pipes, in SQL Server Configuration Manager.
Depending how 'far away' your Azure database is, the delays because of routers and firewalls sometimes upset Kerberos and/or related timings. You can overcome this by using the port in the connection string to avoid the roundtrip to port 1434 to enumerate the instance. I assume you're already using a FQDN. For example: server\instance,port
[edit] so not sure what happened, but we ended up resetting the server and turning off/on TCP/IP and Named Pipes and after a restart and updating the settings everything started working again. weirdest thing. anyways thanks for the help guys.
I'm building a C# WPF application for my job, and I'm getting a weird problem that I've been trying to figure out for the past week. The application connects to the server and imports several tables on start up. So I built it out and was testing it with no issues, but when i pass it to our testers, and everyone is getting the following errors:
Provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server
The users are able to connect to the server through other methods (SSMS/Excel VBA), but just through the application it won't work.
I've checked the following:
Remote connections enabled
TCP/IP connections enabled
Firewall settings are the exact same across all users (me included)
application is compiled as 32 bit (saw this in another thread)
We're using SQL Server 2008 and I've tried several connection strings/methods.
below is the code I'm using to connect:
public void Open_DB_Conn(string Connection_Str)
{
try
{
Sql_Conn = new SqlConnection(Conn_Str);
Sql_Conn.Open();
}
catch (Exception e)
{
MessageBox.Show(string.Format("Error Message:{0} Conn String: {1}",e.Message,Conn_Str));
}
}
Below is my connection string (this is just one of many iterations I've used trying to get it working):
Data Source=IP Address;Initial Catalog=DB_Name;User ID=LOGIN;Password=PWD
Anyone know why I would be the only one able to get it to work and that the users are able to login to the server using other applications without a problem? They use it for logging their excel VBA scripts and there aren't any issues there.
Try this - it may be your answer
"The error is reported by client library. While your server is listeing on remote TCP, client will still try TCP and NP connection in order. So the error client behavior is expected. From what you have described, I believe that even though you enabled the remote TCP connection on the XPSP2 machine, you didn't make the TCP listening port an exception of XPSP2 personal firewall. You should follow steps below to resolve this issue.
check the SQL Server Errorlog to make sure SQL Server is now listening on TCP/IP and confirm which port it is listening on. Usually 1433. In the Errorlog, you will see several lines that discuss what SQL Server is listening on. Below is an example:
2006-01-04 01:41:07.65 server SQL server listening on 10.254.1.150: 1433. <--Shows the IP Address and the port.
2006-01-04 01:41:07.65 server SQL server listening on 127.0.0.1: 1433. <--Shows another IP Address and the port.
2006-01-04 01:41:07.69 server SQL server listening on TCP, Shared Memory, Named Pipes.
2006-01-04 01:41:07.69 server SQL Server is ready for client connections
2, Make sure on Windows XP that the firewall is not blocking that port.
3, go to your client machine and run the client network configuration tool (cliconfg.exe) Make sure TCP/IP is enabled, click properties and make sure the port number is the same one as SQL Server is listening on. Here you can enable NP or disable client NP as well.
Once both the client and the server are using TCP/IP with the same port number and the firewall on server machines is not blocked, you should be able to connect.
Hope this helps."
(Ref: http://social.technet.microsoft.com/Forums/sqlserver/en-US/c488cf76-2515-440f-b3f8-9cfad689c5b6/named-pipes-provider-error-40-could-not-open-a-connection-to-sql-server?forum=sqldataaccess)
You have to configured your SQl server so that other IP can connect it for that you have to gone through mentioned link
Configure SQL server
What authentication are you using for the SQL Server? Windows Authentication or SQL Server authentication? My suggestion is to first turn on SQL Server authentication and use the sa\password to connect to the server. If you are successful, then ask the others (users of your application) to try with the same connection string. Let me know what you find out.
Be sure that the port specified in:
Data Source="IPAddress,port";Initial Catalog=DB_Name;User ID=LOGIN;Password=PWD
matches the port on your SQL Server. You can check that by going on SQL Server COnfiguration Manager and viewing TCP/IP properties.
EDIT :
It is also the case the port defined by blocked by an external firewall. And the rest Applications use other ports. Try to find out which port you can use (if indeed the are restrictions to your network)
Make sure your SQL Server instance is properly configured to use TCP using Sql Server Configuration Manager.
It is by default disabled in SQL Express, as show below.
I'd like to know more about your "Sql_Conn" class.
Also, try using this for your connection.
using (var conn = new SqlConnection(ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString))
{
conn.Open();
using (var cmd = conn.CreateCommand())
{
string cmdText = "SELECT name FROM sys.tables"
cmd.CommandText = cmdText;
cmd.ExecuteNonQuery();
}
}
When I try to do the following code, the program hangs indefinitely. I don't know why and there seems to be other unanswered topics on the matter. Although, if the IP\website cannot be reached, then it works as intended.
private void DoStuff()
{
string connectionString = "Data Source=www.google.com;Connection Timeout=5";
using (SqlConnection connection = new SqlConnection(connectionString))
{
connection.Open(); //Hangs here indefinitely
Console.WriteLine("Test");
}
}
For example, if I set the connection string to
connectionString = "Data Source=www.nonexistentsite.com;Connection Timeout=5";
then it will throw an exception. How do I get it to throw an exception for an active site? ... Also google is just for testing purposes, obviously.
EDIT :
If I try to connect to an unreachable server name or IP address I WILL get this exception...
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: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
UPDATE :
After letting the program run for quite a while, it usually times out finally after 3-5 minutes and gives me the error I posted above. How can I get it to timeout quicker?
If you have set an FQDN (Fully Qualified Domain Name) for your Data Source such as example.com and the DNS server is unable to resolve this FQDN for a long time it is pretty obvious that your request will hang out. Make sure that the machine from which you are running your application can reach the SQL server and resolve it without any issues. Also you probably want to make sure that there is no firewall that might be blocking the request.
Another possible cause for those symptoms is if you have exhausted the connection pool of ADO.NET. This could happen if you have many slow SQL queries running in parallel, each of them taking a physical connection to the database. There is a limit in the number of available connections on this pool and when this limit is reached the next call to connection.Open() might wait for an available connection to be returned to the pool.
Remark: you might also need to specify in your connection string how you want to authenticate against the SQL server. Checkout connectionstrings.com for more examples.
All this is to say that there is absolutely nothing wrong in the C# code you have posted in your question. It looks more like a network related problem that you could bring to the attention of your network administrators.
To get the connection to exit after a specified amount of time without success, you can use the Connection Timeout parameter in the connection string. The number you specify is in seconds, so for example, Connection Timeout=240 is equal to 240 seconds\60 seconds = 4 minutes.
Sample connection string:
<add name="MyConnectionString"
connectionString="
Data Source=MyServer\MSSQL2017;
Initial Catalog=MyDatabase;
Integrated Security=True;
Connection Timeout=10;"/>
In the above connection string, the Open() command will timeout after 10 seconds.