DRAFT KB-XXXX Jboss/Tomcat fails to start with "Too many connections" error in the application server log

Symptoms

Application server fails to start up with the following error observed in the application server log:

ERROR [org.jboss.jca.core.tx.jbossts.XAResourceRecoveryImpl] (Periodic Recovery) IJ000906: Error during crash recovery: jdbc/AppianPrimaryDS (Could not create connection): javax.resource.ResourceException: Could not create connection
	at org.jboss.jca.adapters.jdbc.xa.XAManagedConnectionFactory.getXAManagedConnection(XAManagedConnectionFactory.java:522)
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Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Data source rejected establishment of connection,  message from server: "Too many connections"

Cause

The application server will throw this error when attempting to connect to the database server, all available connections are in use by other clients. This documentation can be used as a reference for more details on this database error.

Action

1. Restart the database which will reset the connections and allow Appian to connect to the database.
2. If this is a recurring issue, then the database team may want to set max_connections variable to a larger value. Please refer to the respective database documentation on how to perform this.

Affected Versions

This article applies to all versions of Appian.