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To set the directive, please go into the Zend Server UI, and go to Administration -> Components (version 2019 or earlier) or Administration -> Extensions (version 2020 or later). For later versions of Zend Server, please make sure Advance View is set on. The Advance View switch is near just above the top of the table, towards the right. Find Zend OPcache on the list of components, and give it one mouse click to expand the directives. On the list of directives, find opcache.optimization_level and set the value to 0 (the decimal digit zero). You can also change the opcache.consistency_checks directive to 1 on this display. Once you change the directive(s), the Save button on the top left of the table becomes enabled. Click the Save button, and when prompted restart Zend Server. The restart takes your web site down for a short while, so please schedule this operation for a time when this would be acceptable.
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