Confluence fails to start with error 'Unknown system variable 'storage_engine'' using MySQL 5.7.x

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Platform notice: Server and Data Center only. This article only applies to Atlassian products on the Server and Data Center platforms.

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

Atlassian only supports running Confluence version 6.3 and above connected to MySQL 5.7. We recommend using a supported version of MySQL (5.5.x and 5.6.x based on your Confluence version). Please see our official Supported Platforms documentation for the list of all the supported platforms for the recent Confluence Versions: Supported Platforms


Confluence fails to start

The following appears in the atlassian-confluence.log

2015-10-31 16:57:07,235 WARN [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1] [mchange.v2.resourcepool.BasicResourcePool] run com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@544beb9c -- 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: Unknown system variable 'storage_engine'



  • MySQL 5.7.x
  • Confluence 6.2.x and below


MySQL 5.7.x uses InnoDB by default, and has removed the storage_engine system variable. Having this variable causes Confluence to fail to start.


Resolution 1:
  • Use a supported database
  • Upgrade to Confluence 6.3.x and above as MySQL 5.7 is supported in that version
Resolution 2:

You may wish to proceed to use Confluence using MySQL 5.7 and the following workaround might solve this issue. However, please note that the reason that we do not support this version with Confluence is because we did not test our product with this database version. Because of this, there might be several compatibility issues within the usage of Confluence product. The term "unsupported" is that we may not be able to help you in troubleshooting issues within your instance should it presents any problem.

Remove the storage_engine parameter from the MySQL JDBC connection string:

  1. Stop Confluence
  2. Edit <confluence-home>/confluence.cfg.xml

    The <confluence_home> directory is the path defined in the following file: <confluence_install>/confluence/WEB-INF/classes/

  3. Look for a line similar to:

    <property name="hibernate.connection.url">jdbc:mysql://localhost/confluence?sessionVariables=storage_engine%3DInnoDB&amp;amp;useUnicode=true&amp;amp;characterEncoding=utf8</property>
  4. Remove storage_engine%3DInnoDB&amp; from the line, it should look like:

    <property name="hibernate.connection.url">jdbc:mysql://localhost/confluence?sessionVariables=useUnicode=true&amp;amp;characterEncoding=utf8</property>
  5. Start Confluence

DescriptionMySQL 5.7.x uses InnoDB by default, and has removed the storage_engine system variable. Having this variable causes Confluence to fail to start.
Last modified on Oct 10, 2018

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