elastic/elasticsearch · error · PluginSyncException

Malformed [proxy], expected [host:port] in [elasticsearch-pl

Error message

Malformed [proxy], expected [host:port] in [elasticsearch-plugins.yml]

What it means

Thrown by PluginsConfig.validate when a non-null proxy string in elasticsearch-plugins.yml does not split into exactly two `:`-separated parts (host:port). This is the first of two malformed-proxy checks (the second, at line 95, re-throws the same message after ProxyUtils.validateProxy fails). PluginSyncException is used.

Source

Thrown at distribution/tools/plugin-cli/src/main/java/org/elasticsearch/plugins/cli/PluginsConfig.java:91

            if (uniquePluginIds.add(plugin.getId()) == false) {
                throw new PluginSyncException("Duplicate plugin ID [" + plugin.getId() + "] found in [elasticsearch-plugins.yml]");
            }
        }

        for (InstallablePlugin plugin : this.plugins) {
            if (officialPlugins.contains(plugin.getId()) == false
                && migratedPlugins.contains(plugin.getId()) == false
                && plugin.getLocation() == null) {
                throw new PluginSyncException(
                    "Must specify location for non-official plugin [" + plugin.getId() + "] in [elasticsearch-plugins.yml]"
                );
            }
        }

        if (this.proxy != null) {
            final String[] parts = this.proxy.split(":");
            if (parts.length != 2) {
                throw new PluginSyncException("Malformed [proxy], expected [host:port] in [elasticsearch-plugins.yml]");
            }

            if (ProxyUtils.validateProxy(parts[0], parts[1]) == false) {
                throw new PluginSyncException("Malformed [proxy], expected [host:port] in [elasticsearch-plugins.yml]");
            }
        }

        for (InstallablePlugin p : plugins) {
            if (p.getLocation() != null) {
                if (p.getLocation().isBlank()) {
                    throw new PluginSyncException("Empty location for plugin [" + p.getId() + "]");
                }

                try {
                    // This also accepts Maven coordinates
                    new URI(p.getLocation());
                } catch (URISyntaxException e) {
                    throw new PluginSyncException("Malformed location for plugin [" + p.getId() + "]");

View on GitHub (pinned to db6a809a66)

Solutions

1. Format the proxy as exactly `host:port`, e.g. `proxy: proxy.internal:8080`.
2. For IPv6 proxies, wrap the host in brackets: `[::1]:8080` so only the port follows the last colon.
3. Re-run after fixing and confirm validateProxy (line 95) no longer fires.

Example fix

# before:
proxy: proxy.internal       # missing port
# or
proxy: http://proxy.internal:8080   # scheme -> too many parts
# after:
proxy: proxy.internal:8080

// Validate proxy shape before deploy.
String proxy = parsed.getProxy();
if (proxy != null && proxy.split(":").length != 2) {
    throw new IllegalArgumentException("proxy must be host:port, got: " + proxy);
}

When it happens

Trigger: validate reads this.proxy; if non-null it splits on `:`. A string with zero, two, or more than one colon (e.g. `host`, `host:port:extra`, or an IPv6-ish literal) yields parts.length != 2 and throws.

Common situations: Proxy configured as bare hostname without port; IPv6 address used raw (colons everywhere); typo like `host =port`; extra whitespace or trailing colons after paste.

Understand the failure class

• Parsing and encoding errors: unexpected token, malformed input — why parsers reject input and how to find the real culprit.

Related errors

• Cannot have null or empty IDs in [elasticsearch-plugins.yml]
• Duplicate plugin ID [{id}] found in [elasticsearch-plugins.y
• Must specify location for non-official plugin [{id}] in [ela
• Empty location for plugin [{id}]
• Malformed location for plugin [{id}]

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/eb108a50afc51fe5. Report an issue: GitHub.