Summary

After upgrading to Confluence 7, startup fails with the following error:

 java.lang.NullPointerException
 at de.communardo.confluence.plugins.apc.filter.APCRedirectAndMetaTagFilter.doFilter(APCRedirectAndMetaTagFilter.java:39)

Environment

Confluence 7.4

Accessibility for Confluence addon version 2.1.1

Diagnosis

Run the following SQL query to confirm this plugin is installed, either in an enabled or disabled state:

SELECT from plugindata where pluginkey ='de.communardo.confluence.plugins.apc';

Cause

The 2.1.1 version of this plugin is not compatible with Confluence 7, and if present, will cause this error upon startup after you upgrade to Confluence 7.

Solution

Option 1

Prior to upgrading to Confluence 7, upgrade the "Accessibility for Confluence" addon to the latest version so that a compatible version will be present once Confluence 7 loads for the first time.  

Option 2

If you've already upgraded, please do the following:

• Stop Confluence 
• Delete the plugin from the database by issuing the following SQL statement:

DELETE from plugindata where pluginkey ='de.communardo.confluence.plugins.apc';

• Start Confluence, verify it will start successfully now
• (optional) Install the latest version of the plugin to restore its functionality or leave it uninstalled if no longer used. 

Note: If you cannot disable this addon using the "Plugin Map" method described in How to remove malfunctioning addons, it may be because the plugin was enabled and never once disabled prior to the upgrade to Confluence 7 and thus will have no entry in the Plugin Map to set to "false". If this is the case, delete it from the PLUGINDATA table as described above.