Upgrade to PHP 7.2 caused error in function counting form input array

You should never update a php/mysql version on a server if you didn't test your application. But that advice is too late now.

What is the content of $this->input('photos') ? I suppose empty or null or something similar?

PHP7.1 accepts this:

count(null);  // result = 0
count(0);  // result = 1
count(1);  // result = 1
count("string");  // result = 1

PHP7.2 does not accept this

count(null);  // warning
count(0);  // warning
count(1);  // warning
count("string");  // warning

// Warning: count(): Parameter must be an array or an object that implements Countable in 

So the fix is to first check if your variable that you want to count is an array or not.

i think you need re-view all the code again, because in difference system, don't know if this help

array_wrap($this->input('photos'));