My site keeps crashing, giving a 404

I’m using Concrete5 and my AWS EC2 instance is running PHP 5.5.9. In the past week, my site has been going down intermittently, displaying a 404 Not Found nginx/1.10.1 error. If I reboot the AWS instance, the site comes back (sometimes only for 5 minutes, sometimes for 5 hours). I’ve checked the Concrete5 logs and I don’t see anything except two types of errors we’ve had since 2018 that never caused us issues before:
Exception Occurred: /var/www/html/site/updates/concrete5.6.3.5_remote_updater/concrete/core/libraries/view.php:994 File /var/www/html/site/updates/concrete5.6.3.5_remote_updater/concrete/themes/cpg/view.php not found. All themes need default.php and view.php files in them. Consult concrete5 documentation on how to create these files. (0)

#0 /var/www/html/site/updates/concrete5.6.3.5_remote_updater/concrete/dispatcher.php(264): Concrete5_Library_View->render(Object(Page))
#1 /var/www/html/site/concrete/startup/updated_core_check.php(6): require(‘/var/www/html/s…’)
#2 /var/www/html/site/concrete/dispatcher.php(14): require(‘/var/www/html/s…’)
#3 /var/www/html/site/index.php(6): require(‘/var/www/html/s…’)
#4 {main}

Exception Occurred: /var/www/html/site/updates/concrete5.6.3.5_remote_updater/concrete/core/controllers/blocks/form.php:258 Oops, something is wrong with the form you posted (it doesn’t have a question set id). (0)

#0 /var/www/html/site/updates/concrete5.6.3.5_remote_updater/concrete/core/models/block.php(411): Concrete5_Controller_Block_Form->action_submit_form()
#1 /var/www/html/site/updates/concrete5.6.3.5_remote_updater/concrete/startup/process.php(358): Concrete5_Model_Block->passThruBlock(‘submit_form’)
#2 /var/www/html/site/updates/concrete5.6.3.5_remote_updater/concrete/dispatcher.php(253): require(‘/var/www/html/s…’)
#3 /var/www/html/site/concrete/startup/updated_core_check.php(6): require(‘/var/www/html/s…’)
#4 /var/www/html/site/concrete/dispatcher.php(14): require(‘/var/www/html/s…’)
#5 /var/www/html/site/index.php(6): require(‘/var/www/html/s…’)
#6 {main}
I’ve checked AWS which shows a higher-than-usual CPU during the problem period but it’s still only 38%. I tried clearing the Concrete5 cache - no luck. Does anyone have any ideas on what the issue could be? TIA

I’d check the nginx logs unless you’ve made changes to your Concrete site recently.

The nginx log shows these errors, over and over again: 09 [error] 927#927: *15640 open() “/usr/share/nginx/html/50x.html” failed (2: No such file or directory)
request: “GET /index.php?cID=434&stackID=446&bID=3688&btask=passthru_stack&ccm_token=1714670259:f9a02f7e8a451e5c760c3e87be103a16&method=submit_form&ccm_paging_p_b2065=10 HTTP/1.1”, upstream: “fastcgi://unix:/var/run/php5-fpm.sock”

2024/07/01 14:23:28 [error] 927#927: *20353 connect() to unix:/var/run/php5-fpm.sock failed (11: Resource temporarily unavailable) while connecting to upstream…request: “GET /index.php?cID=434&stackID=446&bID=3688&btask=passthru_stack&ccm_token=1714785224:5e7bab193c7ffcc89adbc9fd1b52c4e3&method=submit_form&ccm_paging_p_b2065=31 HTTP/1.1”, upstream: “fastcgi://unix:/var/run/php5-fpm.sock:”

Any recommendations for next steps?

Does your theme have a view.php? There seems to be an error about that.

As a side note, as I’m sure you’re aware, this is a pretty old version of Concrete and an end of life version of PHP so it might be a good time to consider a rebuild in newer Concrete + PHP.