How to Fix MySQL Error 2003 (HY000): Can't Connect to Server
Quick Fix Summary
TL;DRVerify the MySQL service is running and the client can reach the server's IP address and port (default 3306) through the network.
MySQL ERROR 2003 (HY000) indicates the client cannot establish a network connection to the MySQL server process. This is a fundamental connectivity failure, not an authentication error.
Diagnosis & Causes
Recovery Steps
Step 1: Verify MySQL Service Status
First, confirm the MySQL server process is actively running on the target host.
# On the MySQL server host
sudo systemctl status mysql
# Or for older systems
sudo service mysql statusStep 2: Check Server Network Binding
Ensure MySQL is listening on a network interface accessible to the client, not just localhost.
sudo netstat -tlnp | grep mysql
# Look for a line like: tcp 0 0 0.0.0.0:3306 0.0.0.0:* LISTEN [PID]/mysqldStep 3: Test Basic Network Connectivity
From the client machine, test if you can reach the server's MySQL port using telnet or netcat.
telnet <server_ip> 3306
# OR
nc -zv <server_ip> 3306Step 4: Inspect and Configure Firewall Rules
Temporarily disable the firewall for testing, or add a rule to allow MySQL traffic.
# For UFW (Ubuntu)
sudo ufw allow 3306/tcp
sudo ufw reload
# For firewalld (RHEL/CentOS)
sudo firewall-cmd --permanent --add-port=3306/tcp
sudo firewall-cmd --reloadStep 5: Verify MySQL Configuration (bind-address)
Check and modify the `bind-address` directive in the MySQL configuration file to allow remote connections.
sudo nano /etc/mysql/mysql.conf.d/mysqld.cnf
# Find and change:
# bind-address = 127.0.0.1
# To:
bind-address = 0.0.0.0
# Save, then restart MySQL
sudo systemctl restart mysqlStep 6: Diagnose with MySQL Client Verbose Output
Use the MySQL client's verbose mode to get detailed error information about the connection attempt.
mysql --verbose --host=<server_ip> --port=3306 --user=<username> -pArchitect's Pro Tip
"In cloud environments (AWS, GCP), ERROR 2003 is often a Security Group or VPC firewall rule issue, not the host's local firewall. Always check the cloud console first."
Frequently Asked Questions
I fixed bind-address and opened the firewall, but still get ERROR 2003. What's next?
Check if the server has multiple network interfaces (public/private). The client must use the IP address of the interface where MySQL is bound. Also, verify the user's host permission in MySQL (`GRANT` statements) allows connection from the client's specific IP or '%'.
What's the difference between ERROR 2003 and ERROR 1045?
ERROR 2003 is a network-layer failure: 'Can't connect to server'. ERROR 1045 is an application-layer failure: 'Access denied'. If you get 1045, you've successfully connected to the MySQL process but failed authentication.