Fix: Kestrel Certificate File Not Found Error

The Error

App start:

System.IO.FileNotFoundException: The specified certificate file could not be found

Quick Fix - 1 Min

1. Path relative to content root. Use Path.Combine(env.ContentRootPath, "cert.pfx"). 2. Copy to output: <CopyToOutputDirectory>PreserveNewest</CopyToOutputDirectory>. 3. Or use cert store: options.ListenAnyIP(443, o => o.UseHttps(StoreName.My, "thumbprint"))

Root Cause

Working directory different in prod. Relative path breaks.