Unable to configure HTTPS endpoint .NET Origin: Application & API Last updated 13 Oct 2026

Unable to configure HTTPS endpoint. No server certificate was specified, and the default developer certificate could not be found or is out of date

Kestrel was told to listen on HTTPS but has no certificate — the ASP.NET Core dev certificate is missing/expired, or production didn’t configure one.

Exact message you may see Unable to configure HTTPS endpointNo server certificate was specified, and the default developer certificate could not be found or is out of datedotnet dev-certs https
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Seen on: .NET

Meaning

In development run dotnet dev-certs https --trust. In containers/production, either terminate TLS at a proxy and listen on HTTP, or configure a certificate (Kestrel:Certificates or ASPNETCORE_Kestrel__Certificates__Default__Path).

Common causes

  • Dev certificate not created/trusted or expired
  • Docker container with https URLs but no certificate
  • Production config expecting a certificate path that doesn’t exist

⚡ Quick fix

  1. dotnet dev-certs https --clean && dotnet dev-certs https --trust
  2. In containers listen on http (ASPNETCORE_URLS=http://+:8080) behind a proxy
  3. Mount and configure a certificate for Kestrel

Detailed fix by platform

Shell

  1. csharp
    dotnet dev-certs https --clean
dotnet dev-certs https --trust
export ASPNETCORE_URLS=http://+:8080

How to diagnose

  1. URLs — ASPNETCORE_URLS / launchSettings
  2. Cert — dev-certs check
  3. Environment — Dev or container?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Application & API. Errors that are often confused with or caused by this one (click to open):

307 — HTTP 307 Temporary Redirect (HTTP)307421 — HTTP 421 Misdirected Request (HTTP)421497 — 400 Bad Request: The plain HTTP request was sent to HTTPS port (Nginx 497) (HTTP)497ATS — App Transport Security has blocked a cleartext HTTP resource load (iOS)ATSAuthentication failed — fatal: Authentication failed for 'https://github.com/x/y.git/' (Git)Authentication failedCERTIFICATE_VERIFY_FAILED — SSL: CERTIFICATE_VERIFY_FAILED / unable to get local issuer certificate (API)CERTIFICATE_VERIFY_FA…CLEARTEXT — CLEARTEXT communication to host not permitted by network security policy (Android)CLEARTEXTFailed to bind to address — System.IO.IOException: Failed to bind to address http://127.0.0.1:5000: address already in use (.NET)Failed to bind to add…Unable to…

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