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Published Sep. 10, 2025

Getting com.mysql.cj.jdbc.exceptions.CommunicationsException on server startup

Written By

Anishq Sharma

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Issue

  • User gets below error on server startup/restart: 
    ERROR [main][DialectDetector:147] com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure__The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. [Sanitized]
    com.mysql.cj.jdbc.exceptions.CommunicationsException: Communications link failure__The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server. [Sanitized]

Environment

  • Liferay DXP 7.0
  • Liferay DXP 7.1
  • Liferay DXP 7.2

Resolution

  • There can be multiple reasons that causes this error.
  • One of the reasons could be usage of SSL.
  • In case, SSL is enabled, please add the following property in JDBC URL: 
    useSSL=true
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