Cannot access <repository> in offline mode

What This Error Means

Maven is running with offline mode enabled (-o / --offline), so it will not contact remote repositories to download missing artifacts.

How to Fix It

1. Disable offline mode and retry the build (remove -o / --offline).
2. If offline mode is set in .mvn/maven.config, remove it (or make it conditional) and re-run the command.
3. If you must run offline (CI/air-gapped), pre-populate the local repository (for example by running the build once online, or by using a repository manager/cache that is reachable from the build environment).
4. Retry the build after artifacts are available locally.

Why It Happens

• Offline mode was enabled intentionally (air-gapped builds, flaky networks) but required artifacts were not pre-cached.
• Offline mode was enabled unintentionally via .mvn/maven.config or a CI template.
• The local repository cache was cleared or is using a different maven.repo.local path than expected.

How to Verify

1. Re-run the original Maven goal and confirm it can resolve dependencies without offline-mode errors.
2. Confirm the previously missing artifacts now exist in ~/.m2/repository/.

Manual offline-mode checks

1. Check your Maven invocation for -o / --offline.
2. Check .mvn/maven.config in the project for -o (offline mode can be enforced there).
3. Confirm whether the missing artifacts exist locally under ~/.m2/repository/.

Common CLI Output

[ERROR] Cannot access central (https://repo.maven.apache.org/maven2) in offline mode and the artifact org.example:lib:jar:1.2.3 has not been downloaded from it before.

[ERROR] Cannot access internal (https://repo.example.com/maven) in offline mode

What Maven offline mode does

1. In offline mode, Maven only uses the local repository cache (~/.m2/repository).
2. If an artifact is missing locally, Maven cannot download it and the build fails.
3. Offline mode can be enabled explicitly on the command line or implicitly via project/CI configuration.

Prevention Tips

• Use a repository manager inside the network so builds do not depend on public internet access.
• If you use offline mode in CI, ensure caches are warmed and persisted between runs.
• Document where offline mode is configured (.mvn/maven.config, CI templates) to avoid surprises.

Where This Can Be Triggered

String msg = "Could not resolve dependencies for project " + project.getId() + ": " + e.getMessage();
DependencyResolutionException dex = new DependencyResolutionException(msg, e);
dex.setResult(e.getResult());
throw dex;