I face this error almost every time I do maintenance on XWiki (restarts, updates, etc) - so not that often. And of course I just have to connect to the MySQL instance and clear the blocked hosts list.
But is there any solution to it? Is it due to a misconfiguration or something?
Hi, doesn’t ring a bell. I don’t remember seeing this.
What is the exact error you get?
Exactly the one I put in the title (with a 500 error page) 
Here’s a full excerpt from the logs:
2022-12-09 10:48:32,564 [XWiki Solr resolve thread] ERROR c.x.x.s.DBCPConnectionProvider - Could not create a DBCP pool. There is an error in the Hibernate configuration file, please review it.
java.sql.SQLException: Cannot create PoolableConnectionFactory (null, message from server: "Host 'xxx.xxx.xxx.xxx' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'")
at org.apache.commons.dbcp2.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:653)
at org.apache.commons.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:531)
at org.apache.commons.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:731)
at com.xpn.xwiki.store.DBCPConnectionProvider.configure(DBCPConnectionProvider.java:225)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.configureService(StandardServiceRegistryImpl.java:107)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:246)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.buildJdbcConnectionAccess(JdbcEnvironmentInitiator.java:146)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:66)
at org.hibernate.engine.jdbc.env.internal.JdbcEnvironmentInitiator.initiateService(JdbcEnvironmentInitiator.java:35)
at org.hibernate.boot.registry.internal.StandardServiceRegistryImpl.initiateService(StandardServiceRegistryImpl.java:101)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.createService(AbstractServiceRegistryImpl.java:263)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:237)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214)
at org.hibernate.id.factory.internal.DefaultIdentifierGeneratorFactory.injectServices(DefaultIdentifierGeneratorFactory.java:175)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.injectDependencies(AbstractServiceRegistryImpl.java:286)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.initializeService(AbstractServiceRegistryImpl.java:243)
at org.hibernate.service.internal.AbstractServiceRegistryImpl.getService(AbstractServiceRegistryImpl.java:214)
at org.hibernate.boot.internal.InFlightMetadataCollectorImpl.<init>(InFlightMetadataCollectorImpl.java:173)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.complete(MetadataBuildingProcess.java:127)
at org.hibernate.boot.model.process.spi.MetadataBuildingProcess.build(MetadataBuildingProcess.java:86)
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:479)
at org.hibernate.boot.internal.MetadataBuilderImpl.build(MetadataBuilderImpl.java:85)
at org.hibernate.cfg.Configuration.buildSessionFactory(Configuration.java:709)
at com.xpn.xwiki.internal.store.hibernate.HibernateStore.build(HibernateStore.java:331)
at com.xpn.xwiki.internal.store.hibernate.HibernateStore.initHibernate(HibernateStore.java:250)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.checkHibernateSynchronized(XWikiHibernateBaseStore.java:481)
at com.xpn.xwiki.store.XWikiHibernateBaseStore.checkHibernate(XWikiHibernateBaseStore.java:474)
at com.xpn.xwiki.store.XWikiHibernateStore.loadXWikiDoc(XWikiHibernateStore.java:1021)
at com.xpn.xwiki.store.XWikiCacheStore.loadXWikiDoc(XWikiCacheStore.java:395)
at com.xpn.xwiki.XWiki.getDocument(XWiki.java:2173)
at com.xpn.xwiki.XWiki.getDocument(XWiki.java:2235)
at org.xwiki.configuration.internal.AbstractXWikiPreferencesConfigurationSource.getBaseObject(AbstractXWikiPreferencesConfigurationSource.java:86)
at org.xwiki.configuration.internal.AbstractXWikiPreferencesConfigurationSource.getBaseProperty(AbstractXWikiPreferencesConfigurationSource.java:139)
at org.xwiki.configuration.internal.AbstractXWikiPreferencesConfigurationSource.getBaseProperty(AbstractXWikiPreferencesConfigurationSource.java:156)
at org.xwiki.configuration.internal.AbstractDocumentConfigurationSource.getPropertyValue(AbstractDocumentConfigurationSource.java:348)
at org.xwiki.configuration.internal.AbstractDocumentConfigurationSource.containsKey(AbstractDocumentConfigurationSource.java:203)
at org.xwiki.configuration.internal.AbstractSpacesConfigurationSource$SpaceConfigurationSource.containsKey(AbstractSpacesConfigurationSource.java:171)
at org.xwiki.configuration.internal.AbstractCompositeConfigurationSource.containsKey(AbstractCompositeConfigurationSource.java:45)
at org.xwiki.configuration.internal.AbstractCompositeConfigurationSource.containsKey(AbstractCompositeConfigurationSource.java:45)
at org.xwiki.configuration.internal.AbstractCompositeConfigurationSource.getProperty(AbstractCompositeConfigurationSource.java:95)
at org.xwiki.url.internal.DefaultURLConfiguration.getURLFormatId(DefaultURLConfiguration.java:58)
at org.xwiki.url.internal.URLExecutionContextInitializer.initialize(URLExecutionContextInitializer.java:55)
at org.xwiki.context.internal.DefaultExecutionContextManager.runInitializers(DefaultExecutionContextManager.java:131)
at org.xwiki.context.internal.DefaultExecutionContextManager.initialize(DefaultExecutionContextManager.java:103)
at com.xpn.xwiki.util.AbstractXWikiRunnable.initExecutionContext(AbstractXWikiRunnable.java:106)
at com.xpn.xwiki.util.AbstractXWikiRunnable.run(AbstractXWikiRunnable.java:125)
at java.base/java.lang.Thread.run(Thread.java:829)
Caused by: java.sql.SQLException: null, message from server: "Host 'xx.xxx.xx.xxx' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'"
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
at com.mysql.cj.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:829)
at com.mysql.cj.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:449)
at com.mysql.cj.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:242)
at com.mysql.cj.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:198)
at org.apache.commons.dbcp2.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:52)
at org.apache.commons.dbcp2.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:374)
at org.apache.commons.dbcp2.BasicDataSource.validateConnectionFactory(BasicDataSource.java:106)
at org.apache.commons.dbcp2.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:649)
... 47 common frames omitted
More info at Host is blocked because of many connection errors MySQL | TablePlus
How do you stop XWiki?
Ha! It could be a shutdown issue, then!
SystemD service, more info here: Tomcat 9 doesn't stop even after 180 seconds