MyCATApache/Mycat-Server · error · ConfigException

[user: ] doesn't exist in [host: ]

Error message

[user: ${user}] doesn't exist in [host: ${hostStr}]

What it means

In loadFirewall, every user named in a <host user="..."> whitelist entry must already exist in the <user> section of server.xml. XMLServerLoader looks the user up in its users map and throws this ConfigException if it is null — i.e., the firewall references a user that was never defined or whose definition failed to load.

Solutions

  1. Add the missing <user name="..."> definition to server.xml, or correct the spelling in the firewall's user attribute to match an existing user
  2. Remove stale firewall user references for users that were intentionally deleted
  3. Grep server.xml to cross-check every user listed in <firewall> against defined <user> names before deploying
  4. Restart MyCat and verify the server.xml loads

Example fix

// before
<user name="alice">...</user> removed, but firewall has:
<host host="10.0.0.1" user="alice"/>
// after
<host host="10.0.0.1" user="bob"/>  <!-- or re-add the alice <user> definition -->
Defensive patterns

Strategy: validation

Validate before calling

// verify firewall users exist in the <user> section
Set<String> defined = new HashSet<>();
NodeList us = doc.getElementsByTagName("user");
for (int i = 0; i < us.getLength(); i++)
    defined.add(((Element) us.item(i)).getAttribute("name"));
for each firewall host element:
    for (String u : e.getAttribute("user").split(","))
        if (!defined.contains(u.trim())) throw new IllegalStateException("Firewall references unknown user: " + u);

Type guard

null

Try / catch

try {
    serverLoader.load();
} catch (ConfigException e) {
    LOG.error("Firewall references undefined user: " + e.getMessage());
    throw new ConfigurationException("Define the user or fix the firewall entry", e);
}

Prevention

When it happens

Trigger: server.xml contains <host host="..." user="alice"> but no <user name="alice"> element exists (or it is misspelled / commented out); firewall section is parsed after users are loaded, so the lookup misses.

Common situations: Renaming a user in the <user> section but not in the firewall whitelist; typo in the user attribute; deleting a user while leaving stale firewall entries; environment-specific overlays where users differ per env.

Understand the failure class

Background: Record Not Found Errors: "not found", RecordNotFound, and "was not found" — what they mean and how to fix them — this error's family across 28 libraries.

Related errors

AI-assisted analysis of MyCATApache/Mycat-Server@65f8d8beb7 (2026-09-11). Data as JSON: /api/errors/47a789756849868c. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/config/loader/xml/XMLServerLoader.java:161

            Node node = list.item(i);
            if (node instanceof Element) {
                Element e = (Element) node;
                String hostStr = e.getAttribute("host").trim();
                String userStr = e.getAttribute("user").trim();
                String []hosts = hostStr.split(",");
                for (String host : hosts) {
                    host = host.trim();
                    if (this.firewall.existsHost(host)) {
                        throw new ConfigException("host duplicated : " + host);
                    }
                }
                String []users = userStr.split(",");
                List<UserConfig> userConfigs = new ArrayList<UserConfig>();
                for(String user : users){
                    user = user.trim();
                	UserConfig uc = this.users.get(user);
                    if (null == uc) {
                        throw new ConfigException("[user: " + user + "] doesn't exist in [host: " + hostStr + "]");
                    }
                    if (uc.getSchemas() == null || uc.getSchemas().size() == 0) {
                        throw new ConfigException("[host: " + hostStr + "] contains one root privileges user: " + user);
                    }
                    userConfigs.add(uc);
                }
                for (String host : hosts) {
                    host = host.trim();
                    if (host.contains("*") || host.contains("%")) {
                        whitehostMask.put(FirewallConfig.getMaskPattern(host), userConfigs);
                    } else {
                        whitehost.put(host, userConfigs);
                    }
                }
            }
        }

        firewall.setWhitehost(whitehost);

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