Business Central, LS Central - Could not connect to localhost

User account needs to be set to login as a service

OR

KB5066835 is installed

 It has come to our attention that Windows 11, October 2025 Cumulative Update (KB5066835) can cause localhost connections to fail. This might affect Hardware Station (HWST) and LS Central connections if hosted locally.

While Microsoft is investigating the underlying cause for this, they have provided two workarounds:

1. Workaround #1: 

1.     In the registry keys, navigate to: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\HTTP\Parameters

2.     Under the Parameters folder, right-click in the right-hand pane and select New > DWORD (32-bit) Value.

3.     Name the value EnableHttp2Tls and set its data to 0 (zero).

4.     Repeat the process to add another value named EnableHttp2Cleartext and set its data to 0.

2. Workaround #2: Uninstall KB5066835.