Magento 2.1 internal server error for specific category when full page cache enable

Question

I had FPC (full page cache) enabled There is one category containing subcategories and 900+ products. it was working fine but suddenly it started pushing 500 internal server error. i have not add any new product or any major change. so now when i disable the FPC, the category start working and when i re enable FPC, again internal server error 500.

i have already applied couple of solutions but no success. tried with removing cache at all, re indexing, crons, have check the htaccess also all things are fine, i had try with creating new category but when i assigned the same block to load on that category, again same issue started.

log is saying that The problem is in the function getIdentities()

can anyone help with this? thanks in advance.

Answer 1

i resolved this issue.

Here is the solution:
When we will have a bulk products in a category we can either enable Varnish cache or Full page cache. we cannot enable both simultaneously, otherwise it will through internal server error if both caches will be enabled.