KB0051 - Various GTSC error codes are displayed to the user


Various GTSC error codes are reported from the list of codes below.


Various GTSC error codes are displayed to the user. Error codes displayed by GTSC come from mstscax.dll. Here is the list off all error codes and their translations from Microsoft TechNet page:

Code 0 meaning = "No information is available."
Code 1 meaning = "Local disconnection. This is not an error code."
Code 2 meaning = _
"Remote disconnection by user. This is not an error code."
Code 3 meaning = _
"Remote disconnection by server. This is not an error code."
Code 260 meaning = "DNS name lookup failure."
Code 262 meaning = "Out of memory."
Code 264 meaning = "Connection timed out."
Code 516 meaning = "WinSock socket connect failure."
Code 518 meaning = "Out of memory."
Code 520 meaning = "Host not found error."
Code 772 meaning = "WinSock send call failure."
Code 774 meaning = "Out of memory."
Code 776 meaning = "Invalid IP address specified."
Code 1028 meaning = "WinSock recv call failure."
Code 1030 meaning = "Invalid security data."
Code 1032 meaning = "Internal error."
Code 1286 meaning = "Invalid encryption method specified."
Code 1288 meaning = "DNS lookup failed."
Code 1540 meaning = "GetHostByName call failed."
Code 1542 meaning = "Invalid server security data."
Code 1544 meaning = "Internal timer error."
Code 1796 meaning = "Timeout occurred."
Code 1798 meaning = "Failed to unpack server certificate."
Code 2052 meaning = "Bad IP address specified."
Code 2056 meaning = "Internal security error."
Code 2308 meaning = "Socket closed."
Code 2310 meaning = "Internal security error."
Code 2312 meaning = "Licensing timeout."
Code 2566 meaning = "Internal security error."
Code 2822 meaning = "Encryption error."
Code 3078 meaning = "Decryption error."


No.1 Mstscax.dll is not registered correctly on the client PC
Sometimes this happens if user was using grdpclient.exe before upgrading to 3.4 and on his PC mstscax.dll is pointing to CD partition of the USB key (because of the old grdpclient used before).

No.2 Other codes like 2056, 2025, 2052, 3078 are displayed if there are issue with TS server or Client settings

No.3 Code 516 is displayed if terminal server or user‘s PC is not responding, or wrong IP/DNS name of terminal server or user PC is specified in the G/On menu action..


Error codes will be converted to the their meaning in the future (3.4.1) version of G/On.

a) include parameter /forceHKCU into the gtsc string
b) try re-register the mstscax.dll using: regsvr32 for e.g. running such line in CMD:
C:\Windows\System32\regsvr32 C:\Windows\System32\mstscax.dll

Code 3078 points to the setting on terminal/client regarding security settings. Try for e.g. on TS to set: “negotiate security”.
If you have users who get Error code 2056, use the solution described in KB0028 - "TS window disappears"

- Terminal server‘s/users PC‘s IP/DNS name in the G/On menu action;
- Verify that terminal server is configured to accept the remote connections and/or users have right to connect;
- Verify if user‘s PC is configured to accept RDP connection and/or user has rights to connect (for e.g. if user has blank password, connection to RDP will nt be possible);
- Make sure the TS server or RDP Desktop is accepting the connections (e.g. connect to terminal server or user‘s PC inside the LAN using mstsc.exe);

Related file


more info on 516 error

my finding on this in two cases was that the windows firewall blocks traffic to - regardless that there is no block rule.
We have explicity created a allow rule fpr and 516 was gone.

If you have a PC showing this problem you can try if this solves the problem.

Best regards Michael

516 error winsock socket connect failure

I wish I had!

2 ways to go:
either restore the system state on the machine to about 28th of May
try to remove all MS updates (one by one) until about 28th of May, testing if 516 error is still there after each update removed

516 error using GTSC both G-On version

I tried to find the roots of the 516 error very hard. After trying all possible solutions, I finally came to the conclusion: most probably Microsoft has release “buggy” Windows update at some point from about May 28th 2010. It is also clear that they have removed that update or replaced it with the “good” one very quickly. This explains why only some computers (not all) and very randomly got 516 error suddenly.

I have confirmed this on 2 computers: XP SP3 Pro 32bit and Win 7 Ultimate 64bit

Here is what I did:
- both PCs had 516 error from about beginning of June 2010
- I have rolled back system state on both computers to may 28th
- after the rollback did MS updates one by one until system was fully updated
- no 516 error anymore

Hope this helps

If I have one more PC with the 516 error I will try to remove the updates one by one until about may 28th. If you have any valuable info pls. share it with me.

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