Title: PHP Warning: Undefined array key “timestamp”
Last modified: June 30, 2024

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# PHP Warning: Undefined array key “timestamp”

 *  Resolved [Juuso Turunen](https://wordpress.org/support/users/juusoturunen/)
 * (@juusoturunen)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/)
 * Hi!
 * First, thank you for this great plugin!
 * There is some PHP warnings when visiting “Cached files” tab (/wp-admin/admin.
   php?page=flush-opcache&tab=cached_files):
 *     ```wp-block-code
       2024/06/30 14:57:51 [error] 435052#435052: *105144 FastCGI sent in stderr: "/www/EXAMPLE.COM/public_html/wp-content/plugins/flush-opcache/admin/class-flush-opcache-cached-files-list.php on line 116; PHP message: PHP Warning:  Undefined array key "timestamp" in /var/www/EXAMPLE.COM/public_html/wp-content/plugins/flush-opcache/admin/class-flush-opcache-cached-files-list.php on line 116; PHP message: PHP Warning:  Undefined array key "timestamp" in /var/www/EXAMPLE.COM/public_html/wp-content/plugins/flush-opcache/admin/class-flush-opcache-cached-files-list.php on line 116; PHP message: PHP Warning:  Undefined array key "timestamp" in /var/www/EXAMPLE.COM/public_html/wp-content/plugins/flush-opcache/admin/class-flush-opcache-cached-files-list.php on line 116; PHP message: PHP Warning:  Undefined array key "timestamp" in /var/www/EXAMPLE.COM/public_html/wp-content/plugins/flush-opcache/admin/class-flush-opcache-cached-files-list.php on line 116; PHP message: PHP Warning:  Undefined array key "timestamp" in /var/www/EXAMPLE.COM/public_html/wp-content/plugins/flush-opcache/admin/class-flush-opcache-cached-files-list.php on line 116; PHP message: PHP Warning:  Undefined array key "timestamp" in /var/www/EXAMPLE.COM/public_html/wp-content/plugins/flush-opcache/admin/class-flush-opcache-cached-files-list.php on line 116; PHP message: PHP Warning:  Undefined array key "timestamp" in /var/www/EXAMPLE.COM/public_html/wp-content/plugins/flush-opcache/admin/class-flush-opcache-cached-files-list.php on line 116; PHP message: PHP Warning:  Undefined array key "timestamp" in /var/www/EXAMPLE.COM/public_html/wp-content/plugins/flush-opcache/admin/class-flush-opcache-cached-files-list.php on line 116; PHP message: PHP Warning:  Undefined array key "timestamp" in /var/www/EXAMPLE.COM/public_html/wp-content/plugins/flush-opcache/admin/class-flush-opcache-cached-files-list.php on line 116; PHP message: PHP Warning:  Undefined array key
       ```
   
 * As you can see there is a lot of same warning in a one “line”. I get several 
   lines these when I refresh page once.
 * Kindly,
   Juuso

Viewing 10 replies - 1 through 10 (of 10 total)

 *  Plugin Author [nierdz](https://wordpress.org/support/users/mnttech/)
 * (@mnttech)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17859787)
 * Hi, I suspect it’s some PHP tuning.
 * Are you using a shared host or your own server ?
 * What version of PHP are you running and what’s the configuration of OPcache ?
 *  Thread Starter [Juuso Turunen](https://wordpress.org/support/users/juusoturunen/)
 * (@juusoturunen)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17860313)
 * Hi!
 * This is my own server.
 * This happens on PHP 8.0 and 8.3.
 *     ```wp-block-code
       Directives	opcache.blacklist_filename	not definedopcache.dups_fix	falseopcache.enable	trueopcache.enable_cli	falseopcache.enable_file_override	falseopcache.error_log	not definedopcache.file_cache	not definedopcache.file_cache_consistency_checks	trueopcache.file_cache_only	falseopcache.file_update_protection	2opcache.force_restart_timeout	180opcache.huge_code_pages	falseopcache.interned_strings_buffer	32opcache.jit	not definedopcache.jit_bisect_limit	0opcache.jit_blacklist_root_trace	16opcache.jit_blacklist_side_trace	8opcache.jit_buffer_size	0opcache.jit_debug	0opcache.jit_hot_func	127opcache.jit_hot_loop	64opcache.jit_hot_return	8opcache.jit_hot_side_exit	8opcache.jit_max_exit_counters	8192opcache.jit_max_loop_unrolls	8opcache.jit_max_polymorphic_calls	2opcache.jit_max_recursive_calls	2opcache.jit_max_recursive_returns	2opcache.jit_max_root_traces	1024opcache.jit_max_side_traces	128opcache.jit_max_trace_length	1024opcache.jit_prof_threshold	0opcache.lockfile_path	/tmpopcache.log_verbosity_level	1opcache.max_accelerated_files	371689opcache.max_file_size	0opcache.max_wasted_percentage	0.05opcache.memory_consumption	2 Gt (2634022912)opcache.opt_debug_level	0opcache.optimization_level	CSE, STRING constructionConstant conversion and jumps++, +=, series of jumpsINIT_FCALL_BY_NAME -> DO_FCALLCFG based optimizationDFA based optimizationCALL GRAPH optimizationSCCP (constant propagation)TMP VAR usageNOP removalMerge equal constantsAdjust used stackRemove unused variablesDCE (dead code elimination)Inline functionsopcache.preferred_memory_model	not definedopcache.preload	/etc/php/preload.phpopcache.preload_user	www-dataopcache.protect_memory	falseopcache.record_warnings	falseopcache.restrict_api	not definedopcache.revalidate_freq	2opcache.revalidate_path	falseopcache.save_comments	trueopcache.use_cwd	trueopcache.validate_permission	falseopcache.validate_root	falseopcache.validate_timestamps	false
       ```
   
 *  Plugin Author [nierdz](https://wordpress.org/support/users/mnttech/)
 * (@mnttech)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17863734)
 * Hi,
 * I’m sorry but I can’t find something in your configuration explaining this…
 * What PHP flavour are you using ? How did you install it ?
 *  Thread Starter [Juuso Turunen](https://wordpress.org/support/users/juusoturunen/)
 * (@juusoturunen)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17863781)
 * Hi
 * This is php-fpm, installing just basic _sudo apt install php8.3-fpm_. And then
   some configurations to the php.ini file, like memory limit etc.
 *  Plugin Author [nierdz](https://wordpress.org/support/users/mnttech/)
 * (@mnttech)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17863797)
 * Can you paste the result of a `php -v` ?
 *  Thread Starter [Juuso Turunen](https://wordpress.org/support/users/juusoturunen/)
 * (@juusoturunen)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17863811)
 * PHP 8.3.8 (cli) (built: Jun 8 2024 21:33:58) (NTS)
   Copyright (c) The PHP GroupZend
   Engine v4.3.8, Copyright (c) Zend Technologieswith Zend OPcache v8.3.8, Copyright(
   c), by Zend Technologies
 *  Thread Starter [Juuso Turunen](https://wordpress.org/support/users/juusoturunen/)
 * (@juusoturunen)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17863850)
 * Okay, it is the opcache.validate_timestamps on php.ini.
 * If it is set to 0, there is no “timestamp” key. After I set it to 1, now I see“
   timestamp” when calling opcache_get_status()
    -  This reply was modified 1 year, 10 months ago by [Juuso Turunen](https://wordpress.org/support/users/juusoturunen/).
 *  Thread Starter [Juuso Turunen](https://wordpress.org/support/users/juusoturunen/)
 * (@juusoturunen)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17863860)
 * But I prefer to keep it set to 0.
 *  Plugin Author [nierdz](https://wordpress.org/support/users/mnttech/)
 * (@mnttech)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17865057)
 * Ok, thank you for this information.
 * This is weird cause I can’t reproduce this behaviour but I’ll filter this warning
   in the next release.
 * And you’re right, in production environment `opcache.validate_timestamps` should
   be disable.
    -  This reply was modified 1 year, 10 months ago by [nierdz](https://wordpress.org/support/users/mnttech/).
 *  Thread Starter [Juuso Turunen](https://wordpress.org/support/users/juusoturunen/)
 * (@juusoturunen)
 * [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17865561)
 * Weird indeed… I just changed the value of `opcache.validate_timestamps` to `1`,
   and of course restarted php process.
 * But any way thank you and keep up the good work! 🙂
 * Juuso

Viewing 10 replies - 1 through 10 (of 10 total)

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## Tags

 * [php](https://wordpress.org/support/topic-tag/php/)
 * [PHP Warning](https://wordpress.org/support/topic-tag/php-warning/)
 * [warning](https://wordpress.org/support/topic-tag/warning/)

 * 10 replies
 * 2 participants
 * Last reply from: [Juuso Turunen](https://wordpress.org/support/users/juusoturunen/)
 * Last activity: [1 year, 10 months ago](https://wordpress.org/support/topic/php-warning-undefined-array-key-timestamp/#post-17865561)
 * Status: resolved