Could not create connection to database server. Attempted reconnect 3 times. Giving

1. Questions

The program connection to the database is abnormal, as follows:

Could not create connection to database server. Attempted reconnect 3 times. Giving 

2. Solutions

I tried a variety of solutions, and finally realized: MySQL connector- java.jar Inconsistent with the latest database version. The database is the latest version of 8

0.19，mysql-connector- java.jar It’s 5.0.6.

Solution: MySQL connector- java.jar Keep the same version number as the database.

The POM file is as follows, please check and modify the version by yourself; some versions are compatible, but it is better to keep them unified.

<dependency>
   <groupId>mysql</groupId>
   <artifactId>mysql-connector-java</artifactId>
   <version>8.0.19</version>
</dependency>