Hello. I keep seeing some random website issues that I think may be related to PHP. I first started noticing problems when our customers would say they're having trouble seeing the site and getting 500 errors. I temporarily set php memory_limit=2G to try to figure this out. I also have opcache enabled.
Environment:
Web-server
Magento 2.3.2
Apache 2.4.41
PHP 7.1.31
Database-server
Mariabdb 10.1
I seeing these errors in the logs and I'm unable to track down the cause.
[php7:error] [pid 22095:tid 140357479417600] [client x.x.x.x:24776] PHP Fatal error: Class Zend\\Stdlib\\Parameters contains 3 abstract methods and must therefore be declared abstract or implement the remaining methods (ArrayAccess::offsetEx0, ArrayAccess::offsetSet, Serializable::unserialize) in /var/www/html/magento/public_html/vendor/zendframework/zend-stdlib/src/Parameters.php on line 14, referer: https://mysite.com
PHP Fatal error: Class Magento\\Framework\\Session\\SaveHandler contains 4 abstract methods and must therefore be declared abstract or implement the remaining methods (SessionHandlerInterface::close, SessionHandlerInterface::read, SHandlerInterface::write, ...) in /var/www/html/magento/public_html/vendor/magento/framework/Session/SaveHandler.php on line 14
I also had a separate Redis server, but thought maybe this was the cause of the problems. So I disabled redis session cache to fallback to native files. These are the first errors I was getting before disabling redis.
PHP Fatal error: session_start(): Failed to initialize storage module: user (path: /var/lib/php/mod_php/session) in /var/www/html/magento/public_html/vendor/magento/framework/Session/SessionManager.php on line 206
[Tue Sep 17 02:29:07.698446 2019] [php7:warn] [pid 26288:tid 140350084826880] [client 94.130.9.183:61150] PHP Warning: Uncaught Magento\\Framework\\Exception\\SessionException: Unable to connect to Redis in /var/www/html/magento/public_html/vendor/magento/framework/Session/SaveHandler/Redis.php:65\nStack trace:\n#0 /var/www/html/magento/public_html/vendor/magento/framework/Session/SaveHandler/Redis.php(81): Magento\\Framework\\Session\\SaveHandler\\Redis->getConnection()\n#1 /var/www/html/magento/public_html/vendor/magento/framework/Session/SaveHandler.php(59): Magento\\Framework\\Session\\SaveHandler\\Redis->open('/var/lib/php/mo...', 'PHPSESSID')\n#2 [internal function]: Magento\\Framework\\Session\\SaveHandler->open('/var/lib/php/mo...', 'PHPSESSID')\n#3 /var/www/html/magento/public_html/vendor/magento/framework/Session/SessionManager.php(206): session_start()\n#4 /var/www/html/magento/public_html/vendor/magento/framework/Interception/Interceptor.php(58): Magento\\Framework\\Session\\SessionManager->start()\n#5 /var/www/html/magento/public_html/vendor/magento/framework/Interception/Interceptor.php(138): Magento\\Framework\\Session\\Generic\\Intercept in /var/www/html/magento/public_html/vendor/magento/framework/Session/SaveHandler/Redis.php on line 65
