Fix error 789 when connecting a VPN

Crashes in Windows are not uncommon, they arise for various reasons and some of them can interfere with access to the network. For example, if you have a connection that uses the L2TP protocol, sometimes you encounter an error with the code 789, which appears on subscribers when they try to start a VPN from a computer directly. Users are not the first to solve such problems on their own, especially when it comes to software failures, hardware problems are harder and more often than not cannot be dispensed with by a specialist. Error 789 VPN reports a failure that occurred at the security level at the time of negotiation with the remote device, but attempts to solve the problem by implementing one more connection in this situation are unsuccessful. Most often, a failure occurs on Windows 7 or 8, but it is possible in other versions of the operating system. If there are no errors in setting up a network connection, and the system is not affected by viruses, the problem lies in the registry. The error is due to the lack of necessary for the full functioning of the files and the need to edit the parameters.

Correction of error 789 when connecting VPN.

What do these registry entries mean

If the L2TP connection attempt failed due to the failure of code 789, the source of the problem is hidden in incorrect authentication based on a pre-key providing the L2TP / IPSec connection. To implement the operation of the process, the keys “ProhibitIpSec” and “AllowL2TPWeakCrypto” are required. Windows cannot standardly create an L2TP connection in the absence of IPSec. So, if the ProhibitIpSec parameter in the registry is set to 1, then a device with Windows 7, 8, 10 OS will not create a filter that uses CA authentication on the machine, then local IP Security policies will be checked. The AllowL2TPWeakCrypto parameter is used to activate MD5 encryption algorithms (Message Digest 5 encrypts any information in 128-bit hash format) and DES (Data Encryption Standard, a standard for symmetric encryption, converts 64-bit data blocks using a 56-bit key). Thus, error 789 when connecting to L2TP suddenly appears when deleting keys that ensure the correct functioning of the VPN channel. They may disappear after installing driver updates, applications, or virus removal.

Useless tips by mistake 789

As usual, when users encounter malfunctions of Windows, they re-read all existing information from the network in the search for solutions to the problem and often face completely ineffectual and sometimes absurd ways. One of the options - error 789 when connecting to L2TP is provoked by choosing the wrong type of VPN. The solution is proposed ingenious:

  • Go to the VPN connection settings and in the “Network” - “VPN type” tab select “Automatic” or “PPTP”.

But after all, we do not have a task to make the L2TP connection work, and the goal is not to find alternatives, and the inclusion of PPTP has nothing to do with setting up the operation of the channel we need. Another of the ridiculous decisions is an appeal to the provider. Although, the call can be effective, because usually the supplier of communication is always ready to contribute to establishing a connection. In this case, he will also help to cope with the task by organizing the arrival of the master.

How To Fix Error 789 L2tp In Windows

We have already found out that when a network is normally configured and Windows functions correctly, where, including virus software is missing, there is a problem in the registry. Editing it manually without existing skills is not recommended, because if the wrong actions are taken, user intervention can lead to the inoperability of the computer and entail irreparable consequences for the operating system. In any case, before working with the registry, it will be better to create a backup. If you are an experienced user, then nothing prevents you from making the necessary changes to the registry entries yourself, thereby eliminating error 789 and then seamlessly connecting to the L2TP connection. We carry out such manipulations:

  • We open the registry in any convenient way (for example, by pressing the Win + R keys, we call the Run console, where we enter the regedit command — the method is universal. When working with Windows 7 and earlier OS versions, you can open the registry via Start, by requesting regedit in the search field).
  • The registry has a tree structure in any version of the OS. So, to resolve the VPN connection error with code 789, go to the HKEY_LOCAL_MACHINE \ System \ CurrentControlSet \ Services \ Rasman \ Parameters branch.

  • Create or adjust existing parameters (set the value 1 in the lines)
    • "ProhibitIpSec" = dword: 00000001
    • “AllowL2TPWeakCrypto” = dword: 00000001.
  • We confirm the action.
  • After the executed manipulations, I reboot the device, which is necessary for the changes to take effect and connect to the Internet.

Having tried this method to resolve error 789, many users note that on Windows 10, 8, 7 the problem no longer occurs.