UnknownHostException Java Origin: Application & API Last updated 13 Oct 2026

java.net.UnknownHostException: api.example.com

DNS resolution failed for the hostname.

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Seen on: Java

Meaning

Typos, internal hostnames not resolvable from this machine, missing DNS inside containers or no network.

Common causes

  • Hostname typo or protocol included
  • Internal DNS / VPN required
  • Container DNS misconfigured
  • Offline

⚡ Quick fix

  1. nslookup the host from the same machine
  2. Fix the configured URL
  3. Check container DNS

Detailed fix by platform

Linux

  1. nslookup api.example.com

How to diagnose

  1. Host — Exact name
  2. DNS — Resolves here?

🔧 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):

0x80072EE7 — Error 0x80072EE7 (Windows Update / Microsoft Store: server name could not be resolved) (Windows)0x80072EE71000 — Cloudflare Error 1000: DNS points to prohibited IP (Cloudflare)10001001 — Cloudflare Error 1001: DNS resolution error (Cloudflare)100114 UNAVAILABLE — gRPC Error: 14 UNAVAILABLE: No connection established / failed to connect to all addresses (API)14 UNAVAILABLEauth/network-request-failed — Firebase Auth: auth/network-request-failed — A network AuthError (such as timeout, interrupted connection or unreachable host) has occurred (Authentication)auth/network-request-…CDN: trunk URL couldn't be downloaded — [!] CDN: trunk URL couldn't be downloaded: https://cdn.cocoapods.org/... (iOS)CDN: trunk URL couldn…ConnectException — java.net.ConnectException: Connection refused (Java)ConnectExceptionCould not resolve host — fatal: unable to access 'https://github.com/…': Could not resolve host: github.com (Git)Could not resolve hostUnknownHo…

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