elastic/elasticsearch · error · IllegalArgumentException

invalid dot validation exception pattern: [{}]

Error message

invalid dot validation exception pattern: [{}]

What it means

IllegalArgumentException thrown while validating the dynamic setting cluster.indices.validate_ignored_dot_patterns: each configured string is compiled with Pattern.compile, and an invalid regex surfaces the offending pattern and chains the PatternSyntaxException as cause. This is a bootstrap-time / settings-update-time guard, not a per-request one.

Source

Thrown at modules/dot-prefix-validation/src/main/java/org/elasticsearch/validation/DotPrefixValidator.java:108

            "\\.monitoring-ent-search-8-.*",
            // data streams defined in files in x-pack/plugin/core/template-resources/src/main/resources/fleet-*:
            "\\.fleet-fileds-fromhost-data-.*",
            "\\.fleet-fileds-fromhost-meta-.*",
            "\\.fleet-fileds-tohost-data-.*",
            "\\.fleet-fileds-tohost-meta-.*",
            // data stream definied in x-pack/plugin/core/template-resources/src/main/resources/kibana-reporting@template.json:
            "\\.kibana-reporting.*",
            // data stream defined in x-pack/plugin/core/template-resources/src/main/resources/slm-history.json:
            "\\.slm-history-7.*",
            // index defined in
            // x-pack/plugin/ent-search/src/main/java/org/elasticsearch/xpack/application/connector/ConnectorTemplateRegistry.java
            "\\.search-acl-filter-.*"
        ),
        (patternList) -> patternList.forEach(pattern -> {
            try {
                Pattern.compile(pattern);
            } catch (PatternSyntaxException e) {
                throw new IllegalArgumentException("invalid dot validation exception pattern: [" + pattern + "]", e);
            }
        }),
        Setting.Property.NodeScope,
        Setting.Property.Dynamic
    );

    DeprecationLogger deprecationLogger = DeprecationLogger.getLogger(DotPrefixValidator.class);

    private final ThreadContext threadContext;
    private final SystemIndices systemIndices;
    private final boolean isEnabled;
    private final boolean isStateless;
    private volatile Set<Pattern> ignoredIndexPatterns;

    public DotPrefixValidator(ThreadContext threadContext, ClusterService clusterService, SystemIndices systemIndices) {
        this.threadContext = threadContext;
        this.systemIndices = systemIndices;
        this.isEnabled = VALIDATE_DOT_PREFIXES.get(clusterService.getSettings());

View on GitHub (pinned to db6a809a66)

Solutions

1. Fix the offending regex entry (proper escaping; Java regex, not glob)
2. Test each pattern with Pattern.compile locally before applying
3. If you need a literal dot prefix, anchor it as "\\.name-.*"

Example fix

// before
PUT _cluster/settings
{"persistent":{"cluster.indices.validate_ignored_dot_patterns":[".myapp-.*"]}} // leading dot is literal but pattern is loose
// after
PUT _cluster/settings
{"persistent":{"cluster.indices.validate_ignored_dot_patterns":["\\.myapp-.*"]}}

// Validate each pattern before applying the setting:
for (String p : patterns) {
    try { Pattern.compile(p); }
    catch (PatternSyntaxException e) { throw new IllegalArgumentException("bad pattern: " + p, e); }
}

try { clusterClient.updateSettings(persistent); }
catch (IllegalArgumentException e) { /* e.getCause() is PatternSyntaxException; fix and retry */ }

When it happens

Trigger: PUT /_cluster/settings updating cluster.indices.validate_ignored_dot_patterns with an entry containing invalid regex syntax (unclosed bracket, dangling meta-char, bad escape). The Setting validator runs on apply.

Common situations: Operator adds a custom ignore pattern with a typo (e.g. missing closing ] or unescaped '.'); copy/paste from docs that lost escaping; expecting glob semantics and writing '*.' instead of '\..*'.

Related errors

• invalid value [{}] must be one of [true,false,limited]
• files entitlement with a 'path_setting' must specify 'basedi
• Index [{}] name beginning with a dot (.) is not allowed
• failed to parse value [{}] for setting [{}], must be [-1b] (
• [painless.regex.enabled] can only be set on node startup.

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/528d6407fe818f00. Report an issue: GitHub.