FIX: The L2TP Connection Attempt Failed Because The Security Layer Encountered A Processing Error

When you’re using Layer 2 Tunneling Protocol (L2TP) for your VPN connection and it doesn’t works, this article may help you. For this protocol to work, the IPSec layer should establish encrypted session with VPN server. If the L2TP layer does not observes any response to its connection request, the VPN connection will fail silently.

In such case, you may receive following error:

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The L2TP connection attempt failed because the security layer encountered a processing error initial negotiations with the remote computer.

The L2TP Connection Attempt Failed Because The Security Layer Encountered A Processing Error

If you’re also victim of this issue, here is how you can resolve it.

FIX: The L2TP Connection Attempt Failed Because The Security Layer Encountered A Processing Error

FIX 1 – Using Services Snap-in

1. Press + R and type services.msc in the Run dialog box, hit Enter key to open Services snap-in.

Services Windows 10

2. In Services snap-in window, locate the IKE and AuthIP IPsec Keying Modules and IPsec Policy Agent services.

The L2TP Connection Attempt Failed Because The Security Layer Encountered A Processing Error

3. Double click on these services and set their Startup type to Automatic and click on Start button to run them. Once these services are running, issue will not occur.

4. Close Services snap-in.

If above solution doesn’t helps, refer FIX 2 below.

FIX 2 – Allow Microsoft CHAP Version 2 Protocol

1. Press + R to open Run, type ncpa.cpl and click OK.

2. Then right click on your VPN connection and select Properties.

3. In the property sheet, switch to Security tab.

The L2TP Connection Attempt Failed Because The Security Layer Encountered A Processing Error

4. Now check the Allow these protocols option and make sure Microsoft CHAP Version 2 (MS-CHAP v2) option is checked. Click Apply and check if the issue is resolved.

If issue still persists, see FIX 3 below.