Jira cloud instance is not opening due to below error

[Praveen Kumar]

The JIRA hosted on our server was accessible but suddenly 8th May 2019 it stopped working.

JIRA version = 7.0.9, Java Version = 1.8.0_51

2019-05-08 18:48:29,354 localhost-startStop-1 INFO [c.a.jira.startup.JiraHomeStartupCheck] The jira.home directory '/var/atlassian/application-data/jira' is validated and locked for exclusive use by this instance.
2019-05-08 18:48:29,565 localhost-startStop-1 INFO [c.a.j.config.database.SystemDatabaseConfigurationLoader] Reading database configuration from /var/atlassian/application-data/jira/dbconfig.xml
2019-05-08 18:48:29,833 localhost-startStop-1 INFO [c.a.jira.startup.JiraStartupLogger] Running JIRA startup checks.
2019-05-08 18:48:29,833 localhost-startStop-1 INFO [c.a.jira.startup.JiraStartupLogger] JIRA pre-database startup checks completed successfully.
2019-05-08 18:48:31,873 localhost-startStop-1 ERROR [NoModule] Error getting datasource via DBCP: JdbcDatasourceInfo{uri='jdbc:mysql://localhost:3306/jira?useUnicode=true&characterEncoding=UTF8&sessionVariables=storage_engine=InnoDB', driverClassName='com.mysql.jdbc.Driver', username='jira', password='********', isolationLevel='null', connectionProperties=null, connectionPoolInfo=ConnectionPoolInfo{maxSize=20, minSize=20, initialSize=null, maxIdle=20, maxWait=30000, sleepTime=300000, lifeTime=600000, deadLockMaxWait=600000, deadLockRetryWait=10000, validationQuery='select 1', minEvictableTimeMillis=60000, timeBetweenEvictionRunsMillis=300000, poolPreparedStatements=null, testOnBorrow=null, testOnReturn=null, testWhileIdle=true, maxOpenPreparedStatements=null, numTestsPerEvictionRun=null, removeAbandonedTimeout=300, validationQueryTimeout=3, defaultCatalog=null}}
org.apache.commons.dbcp.SQLNestedException: Cannot create PoolableConnectionFactory (Unknown database 'jira')

[Vishnukumar Vasudevan]

Can you check below to start from:

1. The jira user has the correct permission to access the database

2. The correct password is given in the config file

3. Database service is running in the server