Unknown cause for internal 500 error

[knyghtly]

I recently decided to do a complete restart on a personal web site that I have maintained for quite a few years. I started this week with a fresh install of Joomla 4.31 with a new database. Everything was running smooth until I started creating articles. Most articles will save normally, but a few will produce the following error:

Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.
Please contact the server administrator at webmaster@[site] to inform them of the time this error occurred, and the actions you performed just before this error.
More information about this error may be available in the server error log.

I have checked the error logs and nothing is being reported. I tried to go back and try to add content to the article paragraph by paragraph. It finally reaches a point where it give the internal service error if you add even one more character. Joomla word count says it is at 803--nothing too crazy. Another one that encounters the same problem is at 439 words.

I can't figure out what is going wrong. I did quite a bit of Googling and forum reading, but nothing I have come across has helped. I would appreciate help form someone with much more technical experience.


Below is the info from FPA:

Joomla! Instance :: Joomla! 4.3.1-Stable (Bora) 2-May-2023
Joomla! Configured :: Yes | Read-Only (444) |
Configuration Options :: Offline: false | SEF: true | SEF Suffix: false | SEF ReWrite: false | .htaccess/web.config: Yes | GZip: false | Cache: false | CacheTime: 15 | CacheHandler: file | CachePlatformPrefix: false | FTP Layer: N/A | Proxy: false | LiveSite: | Session lifetime: 15 | Session handler: database | Shared sessions: false | SSL: 2 | Error Reporting: maximum | Site Debug: true | Language Debug: false | Default Access: Public | Unicode Slugs: false | dbConnection Type: mysqli | PHP Supports J! 4.3.1: Yes | Database Supports J! 4.3.1: Yes | Database Credentials Present: Yes |

Host Configuration :: OS: Linux | OS Version: 5.4.32-grsec-grsec-plus+ | Technology: x86_64 | Web Server: Apache | Encoding: gzip, deflate, br | System TMP Writable: Yes | Free Disk Space : 166.44 GiB |

PHP Configuration :: Version: 8.0.28 | PHP API: cgi-fcgi | Session Path Writable: Yes | Display Errors: 0 | Error Reporting: 22519 | Log Errors To: | Last Known Error: | Register Globals: | Magic Quotes: | Safe Mode: | Allow url fopen: 1 | Open Base: | Uploads: 1 | Max. Upload Size: 512M | Max. POST Size: 512M | Max. Input Time: -1 | Max. Execution Time: 120 | Memory Limit: 128M

Database Configuration :: Version: 8.0.28-0ubuntu0.20.04.3 (Client:mysqlnd 8.0.28) | Database Size: 13.47 MiB | #of Tables with config prefix:  94 | #of other Tables:  0 | User Privileges : GRANT SELECTUser Privileges : INSERTUser Privileges : UPDATEUser Privileges : DELETEUser Privileges : CREATEUser Privileges : DROPUser Privileges : REFERENCESUser Privileges : INDEXUser Privileges : ALTERUser Privileges : CREATE TEMPORARY TABLESUser Privileges : LOCK TABLESUser Privileges : EXECUTEUser Privileges : CREATE VIEWUser Privileges : SHOW VIEWUser Privileges : CREATE ROUTINEUser Privileges : ALTER ROUTINEUser Privileges : TRIGGER

PHP Extensions :: Core (8.0.28) | date (8.0.28) | libxml (8.0.28) | pcre (8.0.28) | sqlite3 (8.0.28) | filter (8.0.28) | hash (8.0.28) | intl (8.0.28) | json (8.0.28) | mbstring (8.0.28) | SPL (8.0.28) | PDO (8.0.28) | Reflection (8.0.28) | session (8.0.28) | pdo_sqlite (8.0.28) | standard (8.0.28) | mysqlnd (mysqlnd 8.0.28) | cgi-fcgi (8.0.28) | bcmath (8.0.28) | bz2 (8.0.28) | calendar (8.0.28) | ctype (8.0.28) | curl (8.0.28) | dom (20031129) | exif (8.0.28) | fileinfo (8.0.28) | ftp (8.0.28) | gd (8.0.28) | gettext (8.0.28) | iconv (8.0.28) | imap (8.0.28) | mysqli (8.0.28) | openssl (8.0.28) | pcntl (8.0.28) | pdo_mysql (8.0.28) | zlib (8.0.28) | posix (8.0.28) | pspell (8.0.28) | sodium (8.0.28) | SimpleXML (8.0.28) | soap (8.0.28) | sockets (8.0.28) | tokenizer (8.0.28) | xml (8.0.28) | xmlreader (8.0.28) | xmlwriter (8.0.28) | xsl (8.0.28) | zip (1.19.5) | Phar (8.0.28) | imagick (3.5.0) | Zend OPcache (8.0.28) | Zend Engine (4.0.28) |
Potential Missing Extensions ::

Switch User Environment :: PHP CGI: Yes | Server SU: Yes | PHP SU: Yes | Potential Ownership Issues: No

Core Folders :: images/ (755) | components/ (755) | modules/ (755) | plugins/ (755) | language/ (755) | templates/ (755) | cache/ (755) | logs/ (755) | tmp/ (755) | administrator/components/ (755) | administrator/modules/ (755) | administrator/language/ (755) | administrator/templates/ (755) | administrator/logs/ (755) | api/ (755) |

Elevated Permissions (First 10) ::

Database statistics :: Uptime: 6446619 | Threads: 8 | Questions: 1816744928 | Slow queries: 35797945 | Opens: 127606736 | Flush tables: 5 | Open tables: 2048 | Queries per second avg: 281.813 |

Components :: Site ::
Core ::
3rd Party::

Components :: Admin ::
Core :: com_banners (4.0.0) 1 | com_ajax (4.0.0) 1 | com_guidedtours (4.3.0) 1 | com_newsfeeds (4.0.0) 1 | com_login (4.0.0) 1 | com_templates (4.0.0) 1 | com_privacy (3.9.0) 1 | com_users (4.0.0) 1 | com_actionlogs (3.9.0) 1 | com_admin (4.0.0) 1 | com_workflow (4.0.0) 1 | com_redirect (4.0.0) 1 | com_modules (4.0.0) 1 | com_languages (4.0.0) 1 | com_associations (4.0.0) 1 | com_contenthistory (4.0.0) 1 | com_tags (4.0.0) 1 | com_scheduler (4.1.0) 1 | com_checkin (4.0.0) 1 | com_menus (4.0.0) 1 | com_plugins (4.0.0) 1 | com_content (4.0.0) 1 | com_postinstall (4.0.0) 1 | com_installer (4.0.0) 1 | com_wrapper (4.0.0) 1 | com_categories (4.0.0) 1 | com_cpanel (4.0.0) 1 | com_fields (4.0.0) 1 | com_finder (4.0.0) 1 | com_joomlaupdate (4.0.3) 1 | com_messages (4.0.0) 1 | com_media (3.0.0) 1 | com_mails (4.0.0) 1 | com_config (4.0.0) 1 | com_cache (4.0.0) 1 |
3rd Party:: com_akeebabackup (9.6.1) 1 | com_gantry5 (5.5.16) 1 | COM_CREATIVECONTACTFORM (4.7.1) 1 |

Modules :: Site ::
Core :: mod_menu (3.0.0) 1 | mod_syndicate (3.0.0) 1 | mod_languages (3.5.0) 1 | mod_whosonline (3.0.0) 1 | mod_articles_latest (3.0.0) 1 | mod_articles_archive (3.0.0) 1 | mod_articles_popular (3.0.0) 1 | mod_articles_category (3.0.0) 1 | mod_wrapper (3.0.0) 1 | mod_related_items (3.0.0) 1 | mod_stats (3.0.0) 1 | mod_tags_popular (3.1.0) 1 | mod_banners (3.0.0) 1 | mod_users_latest (3.0.0) 1 | mod_random_image (3.0.0) 1 | mod_custom (3.0.0) 1 | mod_articles_news (3.0.0) 1 | mod_tags_similar (3.1.0) 1 | mod_feed (3.0.0) 1 | mod_breadcrumbs (3.0.0) 1 | mod_login (3.0.0) 1 | mod_articles_categories (3.0.0) 1 | mod_footer (3.0.0) 1 | mod_finder (3.0.0) 1 |
3rd Party:: mod_gantry5_particle (5.5.16) 1 | MOD_CREATIVECONTACTFORM_NAME (4.7.1) 1 | sigplus (1.5.0.287) 1 |

Modules :: Admin ::
Core :: mod_menu (3.0.0) 1 | mod_privacy_status (4.0.0) 1 | mod_submenu (3.0.0) 1 | mod_privacy_dashboard (3.9.0) 1 | mod_quickicon (3.0.0) 1 | mod_frontend (4.0.0) 1 | mod_latestactions (3.9.0) 1 | mod_user (4.0.0) 1 | mod_messages (4.0.0) 1 | mod_latest (3.0.0) 1 | mod_post_installation_messages (4.0.0) 1 | mod_title (3.0.0) 1 | mod_sampledata (3.8.0) 1 | mod_logged (3.0.0) 1 | mod_version (3.0.0) 1 | mod_stats_admin (3.0.0) 1 | mod_multilangstatus (3.0.0) 1 | mod_custom (3.0.0) 1 | mod_loginsupport (4.0.0) 1 | mod_feed (3.0.0) 1 | mod_login (3.0.0) 1 | mod_popular (3.0.0) 1 | mod_guidedtours (4.3.0) 1 | mod_toolbar (3.0.0) 1 |
3rd Party::

Libraries ::
Core ::
3rd Party::

Plugins ::
Core :: plg_content_joomla (3.0.0) 1 | plg_content_loadmodule (3.0.0) 1 | plg_content_vote (3.0.0) 0 | plg_content_pagebreak (3.0.0) 1 | plg_content_fields (3.7.0) 1 | plg_content_emailcloak (3.0.0) 1 | plg_content_finder (3.0.0) 1 | plg_content_confirmconsent (3.9.0) 0 | plg_content_pagenavigation (3.0.0) 1 | plg_media-action_crop (4.0.0) 1 | plg_media-action_resize (4.0.0) 1 | plg_media-action_rotate (4.0.0) 1 | plg_extension_joomla (3.0.0) 1 | plg_extension_namespacemap (4.0.0) 1 | plg_extension_finder (4.0.0) 1 | plg_multifactorauth_email (4.2.0) 1 | plg_multifactorauth_webauthn (4.2.0) 1 | plg_multifactorauth_fixed (4.2.0) 0 | plg_multifactorauth_yubikey (3.2.0) 1 | plg_multifactorauth_totp (3.2.0) 1 | plg_task_requests (4.1) 1 | plg_task_demo_tasks (4.1) 1 | plg_task_check_files (4.1) 1 | plg_task_site_status (4.1) 1 | plg_captcha_recaptcha (3.4.0) 1 | plg_captcha_recaptcha_invisible (3.8) 1 | plg_system_task_notification (4.1) 1 | plg_system_privacyconsent (3.9.0) 0 | plg_system_httpheaders (4.0.0) 1 | plg_system_cache (3.0.0) 0 | plg_system_logrotation (3.9.0) 1 | plg_system_languagecode (3.0.0) 0 | plg_system_redirect (3.0.0) 0 | plg_system_fields (3.7.0) 1 | plg_system_sessiongc (3.8.6) 1 | plg_system_highlight (3.0.0) 1 | plg_system_webauthn (4.0.0) 1 | plg_system_log (3.0.0) 1 | plg_system_updatenotification (3.5.0) 1 | plg_system_accessibility (4.0.0) 0 | plg_system_jooa11y (4.2.0) 1 | plg_system_languagefilter (3.0.0) 0 | plg_system_actionlogs (3.9.0) 1 | plg_system_remember (3.0.0) 1 | plg_system_sef (3.0.0) 1 | plg_system_guidedtours (4.3.0) 1 | plg_system_stats (3.5.0) 0 | plg_system_schedulerunner (4.1) 1 | plg_system_logout (3.0.0) 1 | plg_system_debug (3.0.0) 1 | plg_system_shortcut (4.2.0) 1 | plg_system_skipto (4.0.0) 1 | plg_authentication_joomla (3.0.0) 1 | plg_authentication_ldap (3.0.0) 0 | plg_authentication_cookie (3.0.0) 1 | plg_installer_packageinstaller (3.6.0) 1 | plg_installer_urlinstaller (3.6.0) 1 | plg_installer_folderinstaller (3.6.0) 1 | plg_installer_override (4.0.0) 1 | plg_installer_webinstaller (4.0.0) 1 | plg_api-authentication_token (4.0.0) 1 | plg_api-authentication_basic (4.0.0) 0 | plg_sampledata_multilang (4.0.0) 1 | plg_filesystem_local (4.0.0) 1 | plg_behaviour_taggable (4.0.0) 1 | plg_behaviour_versionable (4.0.0) 1 | plg_fields_list (3.7.0) 1 | plg_fields_integer (3.7.0) 1 | plg_fields_media (3.7.0) 1 | plg_fields_color (3.7.0) 1 | plg_fields_checkboxes (3.7.0) 1 | plg_fields_radio (3.7.0) 1 | plg_fields_calendar (3.7.0) 1 | plg_fields_url (3.7.0) 1 | plg_fields_editor (3.7.0) 1 | plg_fields_text (3.7.0) 1 | plg_fields_usergrouplist (3.7.0) 1 | plg_fields_imagelist (3.7.0) 1 | plg_fields_textarea (3.7.0) 1 | plg_fields_user (3.7.0) 1 | plg_fields_subform (4.0.0) 1 | plg_fields_sql (3.7.0) 1 | plg_finder_content (3.0.0) 1 | plg_finder_categories (3.0.0) 1 | plg_finder_newsfeeds (3.0.0) 1 | plg_finder_tags (3.0.0) 1 | plg_finder_contacts (3.0.0) 1 | plg_quickicon_joomlaupdate (3.0.0) 1 | plg_quickicon_phpversioncheck (3.7.0) 1 | plg_quickicon_extensionupdate (3.0.0) 1 | plg_quickicon_downloadkey (4.0.0) 1 | plg_quickicon_overridecheck (4.0.0) 1 | plg_quickicon_privacycheck (3.9.0) 1 | plg_editors-xtd_image (3.0.0) 1 | plg_editors-xtd_article (3.0.0) 1 | plg_editors-xtd_pagebreak (3.0.0) 1 | plg_editors-xtd_readmore (3.0.0) 1 | plg_editors-xtd_fields (3.7.0) 1 | plg_editors-xtd_menu (3.7.0) 1 | plg_editors-xtd_module (3.5.0) 1 | plg_webservices_content (4.0.0) 1 | plg_webservices_users (4.0.0) 1 | plg_webservices_templates (4.0.0) 1 | plg_webservices_media (4.1.0) 1 | plg_webservices_messages (4.0.0) 1 | plg_webservices_config (4.0.0) 1 | plg_webservices_installer (4.0.0) 1 | plg_webservices_menus (4.0.0) 1 | plg_webservices_modules (4.0.0) 1 | plg_webservices_redirect (4.0.0) 1 | plg_webservices_languages (4.0.0) 1 | plg_webservices_banners (4.0.0) 1 | plg_webservices_newsfeeds (4.0.0) 1 | plg_webservices_tags (4.0.0) 1 | plg_webservices_privacy (4.0.0) 1 | plg_webservices_plugins (4.0.0) 1 | plg_privacy_content (3.9.0) 1 | plg_privacy_consents (3.9.0) 1 | plg_privacy_message (3.9.0) 1 | plg_privacy_actionlogs (3.9.0) 1 | plg_privacy_user (3.9.0) 1 | plg_actionlog_joomla (3.9.0) 1 | plg_user_terms (3.9.0) 0 | plg_user_joomla (3.0.0) 1 | plg_user_token (3.9.0) 1 | plg_user_contactcreator (3.0.0) 0 | plg_user_profile (3.0.0) 0 | plg_workflow_notification (4.0.0) 1 | plg_workflow_publishing (4.0.0) 1 | plg_workflow_featuring (4.0.0) 1 |
3rd Party:: plg_content_sigplus (1.5.0.287) 1 | plg_system_gantry5 (5.5.16) 1 | Creative Contact Form (4.7.1) 1 | PLG_QUICKICON_AKEEBABACKUP (9.6.1) 1 | plg_quickicon_gantry5 (5.5.16) 1 | plg_editors-xtd_sigplus (1.5.0.287) 0 | plg_editors_tinymce (5.10.7) 1 | plg_editors_codemirror (5.65.12) 1 | plg_gantry5_preset (5.5.16) 0 | plg_search_sigplus (1.5.0.287) 0 |

Templates :: Site :: cassiopeia (1.0) 1 | rt_studius (1.1.0) 1 |
Templates :: Admin :: atum (1.0) 1 |

[toivo]

Even if the option Error Reporting in Global Configuration - Server has been set to 'Maximum', errors are not written into a log file because the FPA results show that the PHP error log has not been set:

Log Errors To: |

Go to Global Configuration, then the Logging tab and set the option 'Log Almost Everything'. Now PHP errors and other messages are written to the log file administrator/logs/everything.php, which you can download using FTP, WinSCP or other tools, available from the cPanel or a similar page, provided by your host.

If the error messages do not identify the possible third party extension as the root cause, you should turn on the option Debug System. However, 128M available memory has been reported to be inadequate for the Debug option. Therefore, unless the cPanel gives you an option to increase the memory to 256M, ask your host to do that, before the Debug System option is turned on.

Alternatively, you could try to disable third party plugins, other than editor plugins TinyMCE and CodeMirror, one at a time, to check which third party plugin causes the issue.

[knyghtly]

I fixed the error reporting issue.

In the "everything" log this is what it says when the 500 error occurs:
2023-06-04T05:45:08+00:00 INFO [IP] controller Holding edit ID com_content.edit.article.42 Array ( [0] => 42 )
2023-06-04T05:45:08+00:00 INFO [IP] controller Checking edit ID com_content.edit.article.42: 1 Array ( [0] => 42 )

In the "deprecated" log, these are the last several lines:
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Joomla\CMS\Factory::getDocument() is deprecated. Load the document from the dependency injection container or via Joomla\CMS\Factory::getApplication()->getDocument(). - [ROOT]/libraries/src/Factory.php - Line 336
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Joomla\CMS\Factory::getLanguage() is deprecated. Load the language from the dependency injection container or via Joomla\CMS\Factory::getApplication()->getLanguage(). - [ROOT]/libraries/src/Factory.php - Line 303
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Joomla\CMS\Factory::getLanguage() is deprecated. Load the language from the dependency injection container or via Joomla\CMS\Factory::getApplication()->getLanguage(). - [ROOT]/libraries/src/Factory.php - Line 303
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Joomla\CMS\Factory::getLanguage() is deprecated. Load the language from the dependency injection container or via Joomla\CMS\Factory::getApplication()->getLanguage(). - [ROOT]/libraries/src/Factory.php - Line 303
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Joomla\CMS\Factory::getDbo() is deprecated. Load the database from the dependency injection container. - [ROOT]/libraries/src/Factory.php - Line 460
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Database is not available in constructor in 6.0. - [ROOT]/libraries/src/MVC/Model/BaseDatabaseModel.php - Line 110
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Since joomla/application 2.0.0: Accessing the input property of Joomla\Application\AbstractWebApplication is deprecated, use the Joomla\Application\AbstractWebApplication::getInput() method instead. - [ROOT]/libraries/vendor/symfony/deprecation-contracts/function.php - Line 25
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Since joomla/application 2.0.0: Accessing the input property of Joomla\Application\AbstractWebApplication is deprecated, use the Joomla\Application\AbstractWebApplication::getInput() method instead. - [ROOT]/libraries/vendor/symfony/deprecation-contracts/function.php - Line 25
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Since joomla/application 2.0.0: Accessing the input property of Joomla\Application\AbstractWebApplication is deprecated, use the Joomla\Application\AbstractWebApplication::getInput() method instead. - [ROOT]/libraries/vendor/symfony/deprecation-contracts/function.php - Line 25
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Since joomla/event 2.0.0: Not passing an event object to Joomla\Event\Dispatcher::dispatch() is deprecated, as of 3.0 the $event argument will be required. - [ROOT]/libraries/vendor/symfony/deprecation-contracts/function.php - Line 25
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Since joomla/event 2.0.0: Not passing an event object to Joomla\Event\Dispatcher::dispatch() is deprecated, as of 3.0 the $event argument will be required. - [ROOT]/libraries/vendor/symfony/deprecation-contracts/function.php - Line 25
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Joomla\CMS\Factory::getLanguage() is deprecated. Load the language from the dependency injection container or via Joomla\CMS\Factory::getApplication()->getLanguage(). - [ROOT]/libraries/src/Factory.php - Line 303
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Joomla\CMS\Factory::getDbo() is deprecated. Load the database from the dependency injection container. - [ROOT]/libraries/src/Factory.php - Line 460
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Database is not available in constructor in 6.0. - [ROOT]/libraries/src/MVC/Model/BaseDatabaseModel.php - Line 110
2023-06-04T05:50:32+00:00 WARNING [IP] deprecated Joomla\CMS\Factory::getDbo() is deprecated. Load the database from the dependency injection container. - [ROOT]/libraries/src/Factory.php - Line 460

[toivo]

Most Deprecated messages can be ignored. They are likely to come from function calls originating in third party extensions that have not yet updated to be fully compatible with Joomla 4. The extensions usually still work in Joomla 4 because those deprecated functions are removed only in major releases, like Joomla 5.0 or Joomla 6.0.

As suggested earlier:

If the error messages do not identify the possible third party extension as the root cause, you should turn on the option Debug System. However, 128M available memory has been reported to be inadequate for the Debug option. Therefore, unless the cPanel gives you an option to increase the memory to 256M, ask your host to do that, before the Debug System option is turned on.

Alternatively, you could try to disable third party plugins, other than editor plugins TinyMCE and CodeMirror, one at a time, to check which third party plugin causes the issue.

[knyghtly]

Thanks for taking the time to help me resolve my issue.

I requested the increase in PHP memory from the host as directed. The only non-core plugins/extensions that were installed before the problem occurred is the Rockettheme template and Gantry 5 (which both ran fine on the old site) and Akeeba backup.

Is there anything else that I should try? I'm scratching my head as most articles will create fine. There are just a few that refuse to work. I can create a new blank article and paste the text in there and it will result in the same error as explained above.

[toivo]

The only non-core plugins/extensions that were installed before the problem occurred is the Rockettheme template and Gantry 5 (which both ran fine on the old site) and Akeeba backup.

According to the FPA, there are a number of third party plugins. Disable or enable each one of them, one by one, to see if one of them causes the issue:

3rd Party:: plg_content_sigplus (1.5.0.287) 1 | plg_system_gantry5 (5.5.16) 1 | Creative Contact Form (4.7.1) 1 | PLG_QUICKICON_AKEEBABACKUP (9.6.1) 1 | plg_quickicon_gantry5 (5.5.16) 1 | plg_editors-xtd_sigplus (1.5.0.287) 0 | plg_gantry5_preset (5.5.16) 0 | plg_search_sigplus (1.5.0.287) 0 |

The plugins with 1 shown after them are enabled and those with 0 are already disabled.

If the error does not happen every time but at random intervals, possibly depending on the content of the article, the disable/enable method may not yield results, unless you manage to find a pattern.

It would be quicker to enable the Debug System option, then create and edit articles like you have normally done before the 500 errors were reported. Once the 500 error occurs, check the last messages in the PHP error log and the log administrator/logs/everything.php, as long as the option 'Log Almost Everything' has been turned on in Global configuration.

[knyghtly]

I turned off all the third party plugins, even the ones that were not installed when the error first started as explained above. Log almost everything is turned on for the server. This is what shows up in the everything php after repeating the same error:

2023-06-05T02:12:25+00:00 INFO [IP] controller Holding edit ID com_content.edit.article.2 Array ( [0] => 43 [1] => 2 )
2023-06-05T02:12:25+00:00 INFO [IP] controller Checking edit ID com_content.edit.article.2: 1 Array ( [0] => 43 [1] => 2 )
2023-06-05T02:12:54+00:00 INFO [IP] controller Holding edit ID com_content.edit.article.2 Array ( [0] => 43 [1] => 2 )
2023-06-05T02:12:55+00:00 INFO [IP] controller Checking edit ID com_content.edit.article.2: 1 Array ( [0] => 43 [1] => 2 )
2023-06-05T02:13:07+00:00 INFO [IP] controller Releasing edit ID com_content.edit.article.2 Array ( [0] => 43 )
2023-06-05T02:15:52+00:00 CRITICAL [IP] error Uncaught Throwable of type Joomla\CMS\Router\Exception\RouteNotFoundException thrown with message "Page not found". Stack trace: #0 [ROOT]/libraries/src/Application/SiteApplication.php(746): Joomla\CMS\Router\Router->parse(Object(Joomla\CMS\Uri\Uri), true)
#1 [ROOT]/libraries/src/Application/SiteApplication.php(232): Joomla\CMS\Application\SiteApplication->route()
#2 [ROOT]/libraries/src/Application/CMSApplication.php(293): Joomla\CMS\Application\SiteApplication->doExecute()
#3 [ROOT]/includes/app.php(61): Joomla\CMS\Application\CMSApplication->execute()
#4 [ROOT]/index.php(32): require_once('/home/collesson...')
#5 {main}
2023-06-05T02:15:57+00:00 CRITICAL [IP] error Uncaught Throwable of type Joomla\CMS\Router\Exception\RouteNotFoundException thrown with message "Page not found". Stack trace: #0 [ROOT]/libraries/src/Application/SiteApplication.php(746): Joomla\CMS\Router\Router->parse(Object(Joomla\CMS\Uri\Uri), true)
#1 [ROOT]/libraries/src/Application/SiteApplication.php(232): Joomla\CMS\Application\SiteApplication->route()
#2 [ROOT]/libraries/src/Application/CMSApplication.php(293): Joomla\CMS\Application\SiteApplication->doExecute()
#3 [ROOT]/includes/app.php(61): Joomla\CMS\Application\CMSApplication->execute()
#4 [ROOT]/index.php(32): require_once('/home/collesson...')
#5 {main}
2023-06-05T02:17:47+00:00 CRITICAL [IP] error Uncaught Throwable of type Joomla\CMS\Router\Exception\RouteNotFoundException thrown with message "Page not found". Stack trace: #0 [ROOT]/libraries/src/Application/SiteApplication.php(746): Joomla\CMS\Router\Router->parse(Object(Joomla\CMS\Uri\Uri), true)
#1 [ROOT]/libraries/src/Application/SiteApplication.php(232): Joomla\CMS\Application\SiteApplication->route()
#2 [ROOT]/libraries/src/Application/CMSApplication.php(293): Joomla\CMS\Application\SiteApplication->doExecute()
#3 [ROOT]/includes/app.php(61): Joomla\CMS\Application\CMSApplication->execute()
#4 [ROOT]/index.php(32): require_once('/home/collesson...')
#5 {main}
2023-06-05T02:19:17+00:00 CRITICAL [IP] error Uncaught Throwable of type Joomla\CMS\Router\Exception\RouteNotFoundException thrown with message "Page not found". Stack trace: #0 [ROOT]/libraries/src/Application/SiteApplication.php(746): Joomla\CMS\Router\Router->parse(Object(Joomla\CMS\Uri\Uri), true)
#1 [ROOT]/libraries/src/Application/SiteApplication.php(232): Joomla\CMS\Application\SiteApplication->route()
#2 [ROOT]/libraries/src/Application/CMSApplication.php(293): Joomla\CMS\Application\SiteApplication->doExecute()
#3 [ROOT]/includes/app.php(61): Joomla\CMS\Application\CMSApplication->execute()
#4 [ROOT]/index.php(32): require_once('/home/collesson...')
#5 {main}

Again, I can take the affected article and save it as is and nothing happens. If I even change a couple of words to bold or h3 it will return the 500 error. I'm stumped.

[toivo]

It sounds really weird, if it is not possible to find any similarities with the pages from where the errors are reported.

Contact your host and ask if the web server has been configured with some ModSecurity rules that are too strict and block normal operations when articles are edited.