NullPointerException at com.atlassian.spring.container.ContainerManager.getComponent()

Problem

In some situations your Confluence system doesn't start anymore with the following error in the logs:

java.lang.NullPointerException
	at com.atlassian.spring.container.ContainerManager.getComponent(ContainerManager.java:33)
	at com.atlassian.confluence.setup.sitemesh.PluginDecoratorMapper.getPluginAccessor(PluginDecoratorMapper.java:74)
	at com.atlassian.confluence.setup.sitemesh.PluginDecoratorMapper.getDecorator(PluginDecoratorMapper.java:23)
	at com.opensymphony.module.sitemesh.mapper.AbstractDecoratorMapper.getDecorator(AbstractDecoratorMapper.java:45)
	at com.opensymphony.module.sitemesh.mapper.InlineDecoratorMapper.getDecorator(InlineDecoratorMapper.java:41)
	at com.atlassian.confluence.util.profiling.ConfluenceDecoratorSelector.selectDecorator(ConfluenceDecoratorSelector.java:59)
	at com.opensymphony.sitemesh.webapp.SiteMeshFilter.doFilter(SiteMeshFilter.java:83)
	...

Environment

All Scroll add ons
All versions

Resolution

This might have several reasons. As this NullPointers are generic, we can't check if the problem is related to one of our products.

To further analyze the problem please perform the following steps to clean the plugin cache

Shutdown your Confluence system.
Delete the content from the following folders:
Usually there shouldn't be any problems with lost data, as these folders contain temporary files. Nevertheless you could copy the folders to be on the safe side before deleting them.
- <confluence-home>/plugins-cache
- <confluence-home>/plugins-osgi-cache
- <confluence-home>/plugins-temp
- <confluence-home>/bundled-plugins
- <confluence-home>/bundled-plugins_language
This will clean the plugin-cache of your system.
Start your Confluence-system again and see if it works afterwards.

Cause

This might have several reasons. As this NullPointers are generic, we can't check if the problem is related to one of our products.