Troubleshooting: Connection Forcibly Closed
This error may occur when connecting to SQL Server using TCP/IP.
Error Text
The error can occur in the following formats:
TCP_PROV: An existing connection was forcibly closed by the remote host.
"ProviderNum: 7, Error: 10054, ErrorMessage: "TCP Provider: An existing connection was forcibly closed by the remote host ..."
Unhandled Exception: A transport-level error has occurred when sending the request to the server. (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.)
Typical Causes of This Error
The following table lists typical causes and resolutions for this error.
Cause |
Resolution |
|---|---|
Client is connecting with an unsupported version of the SQL Server Native Client. |
Update the client computer to the server version of the SQL Server Native Client. |
Faulty network hardware is dropping portions of the TCP traffic. |
Use network monitoring programs to analyze TCP SYN, ACK, and FIN messages. |
The SynAttackProtect setting may be dropping connections. |
See the section "Connections May Be Forcibly Closed When Running on Windows Server 2003 SP1" that follows. |
Connections May Be Forcibly Closed When Running on Windows Server 2003 SP1
When testing scalability with a large number of client connection attempts to an instance of the SQL Server Database Engine running on Windows Server 2003 Service Pack 1 and later, Windows may drop connections if the requests arrive faster than SQL Server can service them. This is a security feature of Windows Server 2003 Service Pack 1 and later, which implements a finite queue for incoming TCP connection requests.
To resolve this issue, use the regedit.exe utility to add the following registry key:
Key |
Type |
Name |
Value |
|---|---|---|---|
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\ |
DWORD |
SynAttackProtect |
00000000 |
.gif "Security note") Security Note |
|---|
Setting this registry key may expose the server to a SYN flood, denial-of-service attack. Add this registry value only if necessary and with an understanding of the security risks. Remove this registry value when testing is complete. |