apache/maven · error · UnsupportedProtocolException

Unspecified protocol

Error message

Unspecified protocol

What it means

Error "Unspecified protocol" thrown in apache/maven.

Source

Thrown at compat/maven-compat/src/main/java/org/apache/maven/repository/legacy/DefaultWagonManager.java:692

        try {
            container.release(wagon);
        } catch (ComponentLifecycleException e) {
            logger.error("Problem releasing wagon - ignoring: " + e.getMessage());
            logger.debug("", e);
        }
    }

    @Override
    @Deprecated
    public Wagon getWagon(Repository repository) throws UnsupportedProtocolException {
        return getWagon(repository.getProtocol());
    }

    @Override
    @Deprecated
    public Wagon getWagon(String protocol) throws UnsupportedProtocolException {
        if (protocol == null) {
            throw new UnsupportedProtocolException("Unspecified protocol");
        }

        String hint = protocol.toLowerCase(java.util.Locale.ENGLISH);

        Wagon wagon;
        try {
            wagon = container.lookup(Wagon.class, hint);
        } catch (ComponentLookupException e) {
            throw new UnsupportedProtocolException(
                    "Cannot find wagon which supports the requested protocol: " + protocol, e);
        }

        return wagon;
    }
}

View on GitHub (pinned to e4093d4e12)

When it happens

Trigger: Thrown at compat/maven-compat/src/main/java/org/apache/maven/repository/legacy/DefaultWagonManager.java:692 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/afcf21ff07f45e82. Report an issue: GitHub.