alibaba/nacos · error · NacosException

400

400

Error message

properties is null

What it means

Thrown by AbstractServerListProvider.init() with error code INVALID_PARAM (400) when the NacosClientProperties argument passed to init is null. This is a defensive null-check at the top of the init method before any property access occurs. Since init() is called internally by the ServerListManager during start(), a null properties object indicates a programming error in the caller or a broken custom provider.

Source

Thrown at client-basic/src/main/java/com/alibaba/nacos/client/address/AbstractServerListProvider.java:43

import java.util.List;

/**
 * Address server list provider.
 * 
 * @author totalo
 */
public abstract class AbstractServerListProvider implements ServerListProvider {
    
    protected String contextPath = ClientBasicParamUtil.getDefaultContextPath();
    
    protected String namespace = "";
    
    @Override
    public void init(final NacosClientProperties properties,
        final NacosRestTemplate nacosRestTemplate) throws NacosException {
        if (null == properties) {
            throw new NacosException(NacosException.INVALID_PARAM, "properties is null");
        }
        initContextPath(properties);
        initNameSpace(properties);
    }
    
    /**
     * Get server list.
     * @return server list
     */
    @Override
    public abstract List<String> getServerList();
    
    /**
     * Get server name.
     * @return server name
     */
    @Override
    public abstract String getServerName();

View on GitHub (pinned to 9b989acdf1)

Solutions

1. Ensure NacosClientProperties is fully constructed and non-null before the ServerListManager.start() is called.
2. If you wrote a custom ServerListProvider, verify super.init(properties, nacosRestTemplate) receives a non-null properties argument.
3. Use NacosClientProperties.PROTOTYPE.derive() to create a valid properties instance rather than passing null.

Example fix

// before (custom provider)
@Override
public void init(NacosRestTemplate template) {
    super.init(null, template);
}

// after
@Override
public void init(NacosClientProperties props, NacosRestTemplate template) throws NacosException {
    super.init(props == null ? NacosClientProperties.PROTOTYPE.derive() : props, template);
}

if (properties == null) {
    properties = NacosClientProperties.PROTOTYPE.derive();
}
serverListProvider.init(properties, restTemplate);

try {
    provider.init(properties, restTemplate);
} catch (NacosException e) {
    if (e.getErrCode() == NacosException.INVALID_PARAM && e.getMessage().contains("properties is null")) {
        properties = NacosClientProperties.PROTOTYPE.derive();
        provider.init(properties, restTemplate);
    } else {
        throw e;
    }
}

When it happens

Trigger: A custom ServerListProvider subclass calls super.init(null, restTemplate); or internal code passes a null properties object due to a lifecycle bug where the manager was constructed before properties were resolved.

Common situations: Custom SPI implementations that override init() but forward a null properties reference; test harnesses that construct providers manually without supplying properties; race conditions during client shutdown where properties are nulled out before init completes.

Related errors

• Agent replacement must not be null
• Agent publish request must not be null
• AgentResourceExt must not be null
• {fieldName} must not be null
• 400

AI-assisted analysis of alibaba/nacos@9b989acdf1 (2026-08-14). Data as JSON: /api/errors/1276921a78b954c9. Report an issue: GitHub.