As a Magento developer I have faced this problem tons of times, I know it is a misconfiguration problem when it occurs some modules are not loaded, neither their routers, causing the error. Most of the times it is solved with no action, other times you may flush the cache
I've read multiple posts about this, trying to debug placing some extra code in Magento core Front controller
app/code/core/Mage/Core/Controller/Varien/Front.php, but at the end this only shows which module routers are missing, not why they are not being loaded. Every time it occurs I try to look which URLs are giving the error, but this is useless information, same as the code trace. It's always the same
Maybe it is caused by module conflicts? Maybe it is some cron task doing something wrong? Maybe some wrong code in older Magento versions? The thing is this problem does not occur since 1.7 version (or if it occurs then it is totally sporadic). I have found some code differences in the main flow, such as
In run() method of
app/code/core/Mage/Core/Model/App.php, or the
check in _initModules() method...
I want to believe there should be someone who has definitively found the cause. Any tips?