Confluence is blocked because of many connection errors
Platform Notice: Data Center Only - This article only applies to Atlassian products on the Data Center platform.
Note that this KB was created for the Data Center version of the product. Data Center KBs for non-Data-Center-specific features may also work for Server versions of the product, however they have not been tested. Support for Server* products ended on February 15th 2024. If you are running a Server product, you can visit the Atlassian Server end of support announcement to review your migration options.
*Except Fisheye and Crucible
Problem
Confluence connects to MySQL database. All of a sudden Confluence becomes inaccessible and the following message appears in the browser:
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Error displayed:
type Exception report
message
description The server encountered an internal error () that prevented it from fulfilling this request.
exception
com.atlassian.util.concurrent.LazyReference$InitializationException: java.lang.NullPointerException
com.atlassian.util.concurrent.LazyReference.getInterruptibly(LazyReference.java:149)
com.atlassian.util.concurrent.LazyReference.get(LazyReference.java:112)
com.atlassian.confluence.setup.ConfluenceEncodingFilter.getGlobalSettings(ConfluenceEncodingFilter.java:45)
com.atlassian.confluence.setup.ConfluenceEncodingFilter.getEncodingInternal(ConfluenceEncodingFilter.java:35)
com.atlassian.confluence.setup.ConfluenceEncodingFilter.getEncoding(ConfluenceEncodingFilter.java:27)
com.atlassian.core.filters.encoding.AbstractEncodingFilter.doFilter(AbstractEncodingFilter.java:38)
com.atlassian.core.filters.AbstractHttpFilter.doFilter(AbstractHttpFilter.java:31)
com.atlassian.core.filters.HeaderSanitisingFilter.doFilter(HeaderSanitisingFilter.java:44)
com.atlassian.confluence.servlet.FourOhFourErrorLoggingFilter.doFilter(FourOhFourErrorLoggingFilter.java:65)
root cause
java.lang.NullPointerExceptionThe following appears in the atlassian-confluence.log
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2015-02-24 18:25:05,509 WARN [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1] [mchange.v2.resourcepool.BasicResourcePool] run com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@171f6647 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception:
java.sql.SQLException: null, message from server: "Host 'confluence' is blocked because of many connection errors; unblock with 'mysqladmin flush-hosts'"
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1072)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:986)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:981)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1104)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2183)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:784)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:46)
at sun.reflect.GeneratedConstructorAccessor30.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:406)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:354)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:284)
at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:134)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:182)
at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:171)
at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
at com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
Cause
MySQL Server blocked the connection of the database to Confluence.
Resolution
This issue originates with the database server so can be resolved by following steps:
Shut down Confluence.
Run mysqladmin flush-hosts on the server running MySQL server.
To avoid this from showing up again:
Increase the max_connect_errors value to a higher value, for example 200. This can be done by editing the file etc/my.cnf (Linux) or my.ini (Windows) configuration file and adding the line set-variable = max_connect_errors=200 below the [mysqld] tag. An example file is shown below:
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[mysqld]
datadir=/backup/mysql
socket=/var/lib/mysql/mysql.sock
user=mysql
set-variable = max_connections=500
set-variable = max_connect_errors=200
old_passwords=1
safe-show-database
skip-locking
skip-innodb
max_allowed_packet = 1M
set-variable = table_cache=1024
set-variable = query_cache_type=1
set-variable = query_cache_limit=1M
set-variable = query_cache_size=128M ## 32MB for every 1GB of RAM
[mysqld_safe]
log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid
[mysql]
socket=/var/lib/mysql/mysql.sock
[mysqladmin]
socket=/var/lib/mysql/mysql.sock
[mysqldump]
socket=/var/lib/mysql/mysql.sockAdditional Notes
If the above steps don't resolve the issue, please check your environment for the following:
Confluence running with Java 11
Mysql 5.7
Mysql Driver version 5.1.4 or 5.1.34
If your configuration contains any of these variables, please follow the diagnostic steps in Confluence is not starting with Mysql and Confluence Java 11. The problem may be a byproduct of the MySQL and TLS protocols.
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