1. Stopped Apache.
2. Modified and saved PHP.ini file
[opcache]
; Determines if Zend OPCache is enabled
opcache.enable=1
; Determines if Zend OPCache is enabled for the CLI version of PHP
opcache.enable_cli=1
; The OPcache shared memory storage size.
opcache.memory_consumption=128
; The amount of memory for interned strings in Mbytes.
opcache.interned_strings_buffer=8
; The maximum number of keys (scripts) in the OPcache hash table.
; Only numbers between 200 and 100000 are allowed.
opcache.max_accelerated_files=4000
...
; How often (in seconds) to check file timestamps for changes to the shared
; memory storage allocation. ("1" means validate once per second, but only
; once per request. "0" means always validate)
opcache.revalidate_freq=60
...
; If enabled, a fast shutdown sequence is used for the accelerated code
opcache.fast_shutdown=1
...
And, I added the zend_extension reference to the PHP.ini file [PHP] section -- important to add it in this section. I added it at the end of the "Paths and Directories" subsection of that PHP section:;;;;;;;;;;;;;;;;;;;;;;;;;
; Paths and Directories ;
;;;;;;;;;;;;;;;;;;;;;;;;;
...
; Tyme added to resolve install issue
zend_extension = "C:\xampp\php\ext\php_opcache.dll"
;;;;;;;;;;;;;;;;
; File Uploads ;
;;;;;;;;;;;;;;;;
3. Restarted Apache.