MySQL rejects a COM_CHANGE_USER request because the supplied credentials are invalid, then closes the connection.
MySQL error 1873 (ER_ACCESS_DENIED_CHANGE_USER_ERROR) appears when a session tries to switch to another database account with bad credentials. Verify the target user exists, grant the right privileges, and resend the COM_CHANGE_USER command with the correct password to resolve the issue.
ER_ACCESS_DENIED_CHANGE_USER_ERROR
MySQL error 1873 signals that the server blocked a connection attempting to switch to a different user account via the COM_CHANGE_USER command without valid credentials. The server immediately terminates the session for security reasons.
The error began appearing in MySQL 5.7.2 and is always accompanied by SQLSTATE 28000, indicating an authentication or authorization failure. Fixing it is essential because the connection is dropped and any in-progress work is lost.
The most common trigger is an application that re-authenticates mid-session with a wrong password or to a user that does not exist. Other factors include revoked privileges, plugin mismatches, and network proxies stripping authentication data.
When the server cannot map the requested user and host combination to a valid account with a matching authentication string, it responds with ER_ACCESS_DENIED_CHANGE_USER_ERROR and disconnects the client.
Start by confirming that the target user exists and has a correct password hash. Next, test a direct login with the same credentials to isolate application issues. Finally, update application connection pools so they stop sending incorrect COM_CHANGE_USER packets.
If password or plugin settings changed recently, run ALTER USER to synchronize credentials and flush privileges. After correcting authentication data, the change-user request will succeed without dropping the session.
Connection pools such as HikariCP often reuse sockets and issue COM_CHANGE_USER when switching databases. A stale password can trigger error 1873. Rotate pool credentials and restart the pool to clear cached sockets.
Replication setups may fail over to a stand-by that lacks the replicated account, causing the error. Provision the user on every replica or use CREATE USER IF NOT EXISTS in deployment scripts.
Keep user accounts consistent across environments with automated migrations. Enforce strong password rotation policies but update application secrets simultaneously. Monitor the MySQL error log for 1873 spikes and alert engineers early.
Using Galaxy, teams can store vetted connection snippets and rotate credentials centrally, ensuring every developer and service uses the same, up-to-date login details, reducing authentication errors.
Error 1045 (28000) appears on initial login failures, while 1873 occurs on mid-session account switches. Error 1396 surfaces when attempting to create a user that already exists. Understanding the distinction accelerates troubleshooting.
The COM_CHANGE_USER packet references a user@host combination that is not defined in mysql.user.
Applications cached an old password hash and now fail re-authentication, producing error 1873.
The account was altered to use caching_sha2_password but the client still sends mysql_native_password data.
GRANT statements were removed or a role was dropped, so the server denies the switch to the requested user.
Occurs on initial connection attempts with invalid credentials. Fix by updating the login string.
Shows up when creating or altering a user that already exists. Use IF NOT EXISTS or DROP USER first.
Forces a password change on first login. Update the password, then reconnect.
Not necessarily. It usually indicates mismatched credentials within your own application. Still, review logs to rule out unauthorized attempts.
No. The command is part of the client protocol. Instead, ensure correct credentials or drop connection pooling features that switch users.
Upgrades often change default authentication plugins. Align the plugin and password hash between server and client libraries.
Galaxy centralizes connection settings and secrets, so every query and script uses tested, endorsed credentials, sharply reducing mismatches.
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