apache/maven · warning · InvalidVersionSpecificationException

Single version must be surrounded by []: {}

Error message

Single version must be surrounded by []: {}

What it means

The per-problem detail line under the toolchains header: each Problem is printed as 'message @ location', where location is the toolchains source file when identifiable, otherwise the default toolchains file path. Fixing every line removes the whole warning block.

Source

Thrown at compat/maven-artifact/src/main/java/org/apache/maven/artifact/versioning/VersionRange.java:173

        cached = new VersionRange(version, restrictions);
        CACHE_SPEC.put(spec, cached);
        return cached;
    }

    private static Restriction parseRestriction(String spec) throws InvalidVersionSpecificationException {
        boolean lowerBoundInclusive = spec.startsWith("[");
        boolean upperBoundInclusive = spec.endsWith("]");

        String process = spec.substring(1, spec.length() - 1).trim();

        Restriction restriction;

        int index = process.indexOf(',');

        if (index < 0) {
            if (!lowerBoundInclusive || !upperBoundInclusive) {
                throw new InvalidVersionSpecificationException("Single version must be surrounded by []: " + spec);
            }

            ArtifactVersion version = new DefaultArtifactVersion(process);

            restriction = new Restriction(version, lowerBoundInclusive, version, upperBoundInclusive);
        } else {
            String lowerBound = process.substring(0, index).trim();
            String upperBound = process.substring(index + 1).trim();

            ArtifactVersion lowerVersion = null;
            if (!lowerBound.isEmpty()) {
                lowerVersion = new DefaultArtifactVersion(lowerBound);
            }
            ArtifactVersion upperVersion = null;
            if (!upperBound.isEmpty()) {
                upperVersion = new DefaultArtifactVersion(upperBound);
            }

View on GitHub (pinned to e4093d4e12)

Solutions

1. Open the file named before the @ and apply the message at the reported position
2. If the location is not a path you recognize, run mvn -X: earlier debug lines show which toolchains sources were read
3. Correct or delete the broken <toolchain> entry and rebuild

for f in ~/.m2/toolchains.xml .mvn/toolchains.xml; do
  [ -f $f ] && xmllint --noout $f
 done

When it happens

Trigger: Any toolchains-building problem: XML that does not parse at that location, a toolchain entry missing required fields, or invalid values detected while merging user and project sources.

Common situations: Multiple toolchains sources (user plus project) making it unclear which file the location refers to; provisioning scripts emitting syntactically valid but semantically incomplete entries.

Related errors

• Only fully-qualified sets allowed in multiple set scenario:
• The artifact has no valid ranges
• Cannot read toolchains file at " + userToolchainsFile.getAbs
• Provides token '" + key + "' doesn't have any value configur
• Java toolchain without the jdkHome configuration element.

AI-assisted analysis of apache/maven@e4093d4e12 (2026-08-21). Data as JSON: /api/errors/2c863c2d4491b67f. Report an issue: GitHub.