Magento FPC throwing “failed to open stream: No such file or directory”

Question

Our Magento started throwing this error for Full Page Cache entries two days ago, and is constantly flooding the log. No errors on front though but it seems , judging by the speed, that it's not cached. So log is full of this:

DEBUG (7): file_get_contents(/...var/full_page_cache//mage--tags/mage---713_CATALOG_PRODUCT_67229): failed to open stream: No such file or directory ...lib/Mage/Cache/Backend/File.php

Installed new magento in a subdir, all works fine. reverted code to three months ago, same error. disabled all custom modules, no effect. permissions seem alright, cause magento can write to all folders.

one peculiar behaviour we noticed is that a file gets created in var/full_page_cache and then immidiately disappears.. only mage--tags stays populated.. we had redis installed and handling FPC, errors started showing up after we disabled it (and Magento fell back to its own FPC)

Any ideas?

UPDATE: The errors get spawned while Navision sync (Using magento api) is working.

Answer 1

Check your cache path from error log:

file_get_contents(/...var/full_page_cache//mage--tags/mage---713_CATALOG_PRODUCT_67229): failed to open stream: No such file or directory ...lib/Mage/Cache/Backend/File.php

Path is incorrect in '...full_page_cache//mage--tags...' part. Change // to / and issue gone.