apache/skywalking · critical · ModuleStartException

No port setting.

Error message

No port setting.

What it means

ModuleStartException thrown by the gRPC configuration-sync provider when the configured port is less than 1 (unset ports default to 0). It is the port counterpart of the host check in initConfigReader() and fails fast before a gRPC channel is created, since port 0 is never a valid explicit target for the config client.

Source

Thrown at oap-server/server-configuration/grpc-configuration-sync/src/main/java/org/apache/skywalking/oap/server/configuration/grpc/GRPCConfigurationProvider.java:60

            @Override
            public Class type() {
                return RemoteEndpointSettings.class;
            }

            @Override
            public void onInitialized(final RemoteEndpointSettings initialized) {
                settings = initialized;
            }
        };
    }

    @Override
    protected ConfigWatcherRegister initConfigReader() throws ModuleStartException {
        if (Strings.isNullOrEmpty(settings.getHost())) {
            throw new ModuleStartException("No host setting.");
        }
        if (settings.getPort() < 1) {
            throw new ModuleStartException("No port setting.");
        }

        return new GRPCConfigWatcherRegister(settings);
    }
}

View on GitHub (pinned to 102af09b4a)

Solutions

1. Set a valid port under configuration.grpc, e.g. port: 9555
2. Check the env substitution variable (e.g. ${SW_GRPC_PORT}) is set and numeric
3. Restart OAP

Example fix

# before
grpc:
  host: config-server.internal
# port missing

# after
grpc:
  host: config-server.internal
  port: 9555

int port = Integer.parseInt(System.getenv().getOrDefault("SW_CONFIGURATION_GRPC_PORT", "0"));
if (port < 1 || port > 65535) {
    throw new IllegalStateException("configuration.grpc port must be 1-65535");
}

When it happens

Trigger: configuration.selector: grpc with the port key omitted (defaults to 0), set to 0 or a negative number, or a port placeholder variable that parses to 0. settings.getPort() < 1 triggers the throw.

Common situations: Template config that ships with port commented out; port defined as a string with a typo (parsed back to default); copying host but not port when migrating from another provider.

Related errors

• No host setting.
• admin-server: gRPCPort must be > 0 when the module is enable
• admin-server: failed to start gRPC server
• Zookeeper hostPort cannot be null or empty.
• Zookeeper namespace cannot be null or empty.

AI-assisted analysis of apache/skywalking@102af09b4a (2026-08-14). Data as JSON: /api/errors/7140c9025a06bbcc. Report an issue: GitHub.