When previewing a variation in Pages App the language switching has no effect and in the logs the following stack trace shows up:

016-02-01 18:46:26,421 ERROR info.magnolia.rendering.engine.RenderingFilter    : RepositoryException while reading Resource [/travel/de]
javax.jcr.PathNotFoundException: /travel/de
	at org.apache.jackrabbit.core.ItemManager.getNode(ItemManager.java:577)
	[..]

This was found after fixing MAGNOLIA-6518.

Howto reproduce

In travel-demo

• Import variations in site definition:
  • In CE import config.modules.travel-demo.config.travel.variations.xml
  • In EE import config.modules.multisite.config.sites.travel.variations.xml
• switch to preview mode
• switch to tablet or smartphone variation
• switch from English to German

Source of problem

The problem seems to be at info.magnolia.module.site.filters.SiteMergeFilter.doFilter(HttpServletRequest, HttpServletResponse, FilterChain) in the code block starting at line #96, that is if there are variations. The fakeSite (an instance of info.magnolia.module.site.ConfiguredSite) used to merge with variations gets the default info.magnolia.cms.i18n.I18nContentSupport configuration which turns out not to be able to resolve Locale s correctly (only new Locale("en") is set as fallback). This also breaks the currentUri in the aggregationState so that code eventually ends in the path shown above with an actually non existing URI /travel/de hence the failure.

Possible solutions

Inheriting the i18n-settings from the current site

The following snippet in SiteMergerFilter seems to do the trick:

...
final ConfiguredSite fakeSiteWithProperName = (ConfiguredSite) Components.newInstance(clazz);
fakeSiteWithProperName.setName(currentSite.getName());
fakeSiteWithProperName.setI18n(currentSite.getI18n()); // Use the i18n setting from the currentSite
...

Downside: this makes it impossible to set a custom i18n support for a variation (as it would be overwritten).

Move fallback from site to SiteI18nContentSupport

Instead of setting the DefaultI18nContentSupport in the ConfiguredSite we could instead return a new instance of DefaultI18nContentSupport when info.magnolia.module.site.i18n.SiteI18nContentSupport#getI18nContentSupport() encounters an i18n support of null for the current site.

See: https://gist.github.com/anonymous/b989610f7059a29e0229