Error 2025 indicates the client (usually a replica) could not establish a network session with the master server during replication setup or probing.
MySQL Error 2025: CR_PROBE_MASTER_CONNECT appears when a replica cannot reach its master due to wrong host, port, credentials, or network blocks. Verify master host, open port 3306, test credentials, and restart replication to resolve the issue.
Error connecting to master: CR_PROBE_MASTER_CONNECT was removed after 8.0.32.
MySQL raises Error 2025 when a client, most often a replica, fails to open a TCP session with its master while probing or during CHANGE MASTER TO. Versions after 8.0.32 removed the symbolic name, but the numeric code still appears in logs produced by older connectors.
The message confirms the failure occurred at the network handshake stage, before any authentication packets were exchanged.
Fixing the connection path is therefore the priority.
Error 2025 surfaces during START SLAVE, START REPLICA, mysqlpump --include-master-host, or custom tooling that calls mysql_real_connect to a replication master.
It can also pop up in application code compiled against pre-8.0.32 headers.
Administrators often see it immediately after a failover, IP change, or firewall update because the replica still tries the old endpoint.
Replication stops while the error persists, causing lag, stale read traffic, and potential data loss in disaster-recovery topologies. Prompt remediation restores high availability and keeps read replicas consistent.
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Typos in CHANGE MASTER TO or an outdated DNS entry prevent the replica from locating the master.
Port 3306 (or a custom MySQL port) may be closed between servers, dropping TCP SYN packets.
The master may be stopped, crashed, or stuck in maintenance mode, refusing connections.
GRANT statements that restrict host access (e.g., 'repl'@'10.%') can reject the replica’s IP.
For SSL-enabled channels, missing certificates or ciphers stop the handshake before authentication.
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The symbolic name was removed, but older connectors and custom code can still emit numeric code 2025. The underlying connection failure remains relevant.
No. The most common reason is a mismatched host or port. Check DNS records and CHANGE MASTER parameters before restarting services.
Yes. Galaxy’s connection tester validates hostname, port, and credentials before saving a replica profile, reducing typos that cause Error 2025.
Only if the connection parameters are correct and the master is reachable. Restarting alone does not solve network or credential problems.
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