Troubleshooting Network Loopback Restrictions in UWP Apps

Problem:

UWP applications attempting to connect to a local CouchDB instance (or similar local server) on "localhost" (127.0.0.1) may fail with a "net_http_client_execution_error".

Cause:

Windows' default security settings restrict UWP apps from accessing localhost to enhance network security.

Resolution:

To permit localhost access for your UWP application, follow these steps:

1. Find Your Package Family Name: Locate your UWP app's package family name. You can find this using Visual Studio 2015's Package.appxmanifest editor or the PowerShell command Get-AppxPackage. The name will have a format like "MyPackage_edj12ye0wwgwa".

2. Grant Loopback Access: Open an elevated command prompt (run as administrator) and execute this command, replacing with your app's actual package family name:

c:\>checknetisolation loopbackexempt -a -n=

3. (Optional) Revoke Loopback Access: To remove the loopback exemption, use this command in an elevated command prompt:

c:\>checknetisolation loopbackexempt -d -n=

4. Reset Loopback Exemptions (if needed): If loopback exemptions become unreliable, clear all exemptions and reapply them individually using:

c:\>checknetisolation loopbackexempt -c

Important Considerations:

• Consult Microsoft's official documentation (https://msdn.microsoft.com/en-us/library/windows/apps/dn640582.aspx) for detailed information.
• This solution applies exclusively to UWP applications; other application types may require different approaches.