elastic/elasticsearch · error · GradleException

tests.bwc.git_fetch_latest must be [true] or [false] but was

Error message

tests.bwc.git_fetch_latest must be [true] or [false] but was [${fetchProp}]

What it means

Thrown as GradleException inside the fetchLatest task configuration when the system property tests.bwc.git_fetch_latest is set to a value other than "true" or "false". The property controls whether the BWC git checkout fetches latest from remotes; the provider maps the string to a boolean and rejects anything ambiguous rather than silently defaulting.

Source

Thrown at build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/InternalBwcGitPlugin.java:123

                        // for testing only we can override the base remote url
                        String remoteRepoUrl = providerFactory.systemProperty("testRemoteRepo")
                            .getOrElse("https://github.com/" + remoteRepo + "/" + rootProjectName);
                        spec.commandLine("git", "remote", "add", remoteRepo, remoteRepoUrl);
                    });
                }
            });
        });

        boolean isOffline = project.getGradle().getStartParameter().isOffline();
        TaskProvider<LoggedExec> fetchLatestTaskProvider = tasks.register("fetchLatest", LoggedExec.class, fetchLatest -> {
            var gitFetchLatest = providerFactory.systemProperty("tests.bwc.git_fetch_latest").orElse("true").map(fetchProp -> {
                if ("true".equals(fetchProp)) {
                    return true;
                }
                if ("false".equals(fetchProp)) {
                    return false;
                }
                throw new GradleException("tests.bwc.git_fetch_latest must be [true] or [false] but was [" + fetchProp + "]");
            });
            fetchLatest.onlyIf("DRA snapshot not available", task -> draBuildId.get().isEmpty());
            fetchLatest.onlyIf("online and gitFetchLatest == true", t -> isOffline == false && gitFetchLatest.get());
            fetchLatest.dependsOn(addRemoteTaskProvider);
            fetchLatest.getWorkingDir().set(gitExtension.getCheckoutDir());
            // Fetch latest from remotes, including tags, overriding any existing local refs
            fetchLatest.commandLine("git", "fetch", "--all", "--tags", "--force");
        });

        String projectPath = project.getPath();
        TaskProvider<Task> checkoutBwcBranchTaskProvider = tasks.register("checkoutBwcBranch", checkoutBwcBranch -> {
            checkoutBwcBranch.dependsOn(fetchLatestTaskProvider);
            checkoutBwcBranch.onlyIf("DRA snapshot not available", task -> draBuildId.get().isEmpty());
            ExtraPropertiesExtension taskExtensionsProperties = checkoutBwcBranch.getExtensions().getExtraProperties();
            checkoutBwcBranch.doLast(new Action<Task>() {
                @Override
                public void execute(Task task) {
                    File checkoutDir = gitExtension.getCheckoutDir().get();

View on GitHub (pinned to db6a809a66)

Solutions

Set the property to exactly true or false (lowercase): -Dtests.bwc.git_fetch_latest=false.
Omit the property entirely to accept the default (true).
Check the CI/shell script for unquoted variables or trailing whitespace that corrupts the value.

Example fix

# before
./gradlew bwcTest -Dtests.bwc.git_fetch_latest=1

# after
./gradlew bwcTest -Dtests.bwc.git_fetch_latest=false

Defensive patterns

Strategy: validation

Validate before calling

String v = System.getProperty("tests.bwc.git_fetch_latest", "true");
if ("true".equalsIgnoreCase(v) == false && "false".equalsIgnoreCase(v) == false) {
    throw new IllegalArgumentException("Invalid value for tests.bwc.git_fetch_latest: " + v);
}

Prevention

Always use lowercase 'true' or 'false' for tests.bwc.git_fetch_latest.
Quote shell variables when passing system properties in CI scripts.
Omit the property to accept the default (true) when in doubt.
Validate property values in a pre-check script before invoking Gradle.

When it happens

Trigger: At line 116 the providerFactory resolves tests.bwc.git_fetch_latest (defaulting to "true") and runs a map that checks for exactly "true" or "false". Passing -Dtests.bwc.git_fetch_latest=yes, =1, =TRUE (case-sensitive), or an empty trailing value triggers the throw at line 123.

Common situations: Developer passes -Dtests.bwc.git_fetch_latest=1 or =yes expecting truthiness; CI script sets the property from an unquoted shell variable that resolves to empty; copy-paste of a property name with a trailing space; case mismatch (TRUE vs true).

Related errors

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/bfd6904753f9e5fe. Report an issue: GitHub.