installed.jpg causing huge error logs!

I have a dedicated server with a number of client websites installed on it. I've been having an issue with very large error log files being generated which are filling up the space on the server, Today one client's website went down completely because they had used all their allocated space on the server thanks to the error log file, and this is the error reported by the hosting company:

"The largest use of space I can see for the site is the 8.4Gb error log, this is filling up very rapidly as this error Is being generated every minute.

[Thu Mar 03 09:57:02 2016] [error] [client 80.68.56.66] PHP Warning: date(): It is not safe to rely on the system's
timezone settings. You are *required* to use the date.timezone setting or the date_default_timezone_set() function. In
case you used any of those methods and you are still getting this warning, you most likely misspelled the timezone
identifier. We selected 'UTC' for 'GMT/0.0/no DST' instead in
/var/www/vhosts/[websiteaddress.com]/httpdocs/images/installed.jpg on line 2, referer: http://www.websiteaddress.com/

I have already put default timezone settings on any page using the strtotime function, but it would appear that it's the installed.jpg image file that's causing the problem. We have PowerCMS on several sites so this error is likely happening on all of them. We don't even use it in the CMS, so can it be removed from the WA_Globals.php file? How would I do that?

The best solution would be to add the time zone setting to the php.ini file so you don't need it on the page. That would prevent any errors moving forward.

You could also add the date_default_timezone_set() function call to the top of the globals.php file to prevent issues with this particular file. It is definitely better to do it in the php.ini file so you don't have to worry about it every time the date() function is used in php.

I probably shouldn't add it to the php.ini file as I host sites for clients in different countries/timezones. I'll try adding it to the WA_Globals.php file and see if that sorts it.

By not specifying one it will always use 'UTC' anyway, so you might as well set it to prevent your clients from having similar error logs. They can still always overwrite it with date_default_timezone_set().