gradle/gradle · error · GradleException

Duplicate configuration for repository '<name>'.

Error message

Duplicate configuration for repository '<name>'.

What it means

DefaultJavaToolchainRepositoryHandler.configureRepository creates the repository and adds it to a Set; DefaultJavaToolchainRepository equality is keyed by name, so repositories.add returning false means a repository with that name was already configured, and the duplicate declaration throws GradleException 'Duplicate configuration for repository <name>'.

Source

Thrown at platforms/jvm/toolchains-jvm/src/main/java/org/gradle/jvm/toolchain/internal/DefaultJavaToolchainRepositoryHandler.java:102

        }
    }

    @Override
    public void repository(String name, Action<? super JavaToolchainRepository> configureAction) {
        assertMutable();

        DefaultAuthenticationContainer authenticationContainer = new DefaultAuthenticationContainer(instantiator, CollectionCallbackActionDecorator.NOOP);
        for (Map.Entry<Class<Authentication>, Class<? extends Authentication>> e : authenticationSchemeRegistry.getRegisteredSchemes().entrySet()) {
            authenticationContainer.registerBinding(e.getKey(), e.getValue());
        }
        AuthenticationSupporter authenticationSupporter = new AuthenticationSupporter(instantiator, objectFactory, authenticationContainer, providerFactory);

        DefaultJavaToolchainRepository repository = objectFactory.newInstance(DefaultJavaToolchainRepository.class, name, authenticationContainer, authenticationSupporter, providerFactory);
        configureAction.execute(repository);

        boolean isNew = repositories.add(repository);
        if (!isNew) {
            throw new GradleException("Duplicate configuration for repository '" + name + "'.");
        }
    }

    @Override
    public List<JavaToolchainRepository> getAsList() {
        ArrayList<JavaToolchainRepository> copy = repositories.stream()
                .map(it -> (JavaToolchainRepositoryInternal) it)
                .map(ImmutableJavaToolchainRepository::new)
                .collect(Collectors.toCollection(ArrayList::new));
        return Collections.unmodifiableList(copy);
    }

    @Override
    public int size() {
        return repositories.size();
    }

    @Override

View on GitHub (pinned to 534f27719b)

Solutions

1. Give each repository declaration a unique name in toolchainManagement.repositories
2. Check settings plugins you apply - one of them may already declare the same repository name
3. Consolidate the duplicate declarations into a single block (or move ownership fully into the plugin)

Example fix

// before - settings.gradle.kts declares 'nexus' twice
repositories { nexus { ... } }
repositories { nexus { ... } }  // Duplicate configuration

// after
repositories { nexus { ... } }
repositories { vendorMirror { ... } }

// settings lint: no duplicate repository declarations
def names = []
settings.toolchainManagement.repositories.getAsList().each { names << it.name }
assert names == names.toUnique().toList() : 'duplicate toolchain repository names'

When it happens

Trigger: Two declareRepository blocks (or a settings plugin plus the settings script) declare repositories with the same name under toolchainManagement.repositories in settings evaluation.

Common situations: Copying an example block and forgetting to rename it; a convention/settings plugin and the local settings.gradle.kts both declaring 'myRepo'; refactoring that accidentally left the old block in place.

Related errors

• Mutation of toolchain repositories declared in settings is o
• Duplicate registration for '<className>'.
• Cannot add '%s' to '%s' as it is a filtered collection
• Toolchain installation '{}' could not be probed: {}
• Toolchain installation '{}' does not provide the required ca

AI-assisted analysis of gradle/gradle@534f27719b (2026-08-22). Data as JSON: /api/errors/2d9b2cb52e31aebe. Report an issue: GitHub.