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--- litespeed_wiki:config:understanding_500 [2018/05/16 15:10]
Jackson Zhang [Run out of Memory on php.ini]
+++ litespeed_wiki:config:understanding_500 [2019/12/10 14:50]
Shivam Saluja Added SIGUSR2 Method.
@@ Line 1: / Line 1: @@
 ====== Understanding 500 Internal Server Error ======
-The 500 status code, or Internal Server Error, means that server cannot process the request for an unknown reason. Sometimes this code will appear when more specific 5xx errors are more appropriate.
+The 500 status code, or "Internal Server Error," means that the server cannot process the request for an unknown reason. Sometimes this code will appear when more specific 5xx errors are more appropriate.
-This most common cause for this error is server misconfiguration (e.g. a malformed .htaccess file) or missing packages (e.g. trying to execute a PHP file without PHP installed properly), permission or ownership changes, Improperly configured php.ini, a PHP upgrade ...etc, anything can trigger a 500 error in a website. The impact of the error can vary based on the cause that triggered it.
+The most common causes for this error are server misconfiguration (e.g. a malformed ''.htaccess'' file), missing packages (e.g. trying to execute a PHP file without PHP installed properly), permission or ownership changes, improperly configured ''php.ini'', a PHP upgrade, etc. //Anything// that the server doesn't know how to handle can trigger a 500 error in a website. The impact of the error can vary based on the event that triggered it.
-error is not a LiteSpeed web server specific error. If you use a control panel like cpanel, you can try the same steps with apache. Most likely Apache will return the same 500 error as LSWS. You will need to find out the reason which causes the problem. If it does not happen to apache server but only on LSWS, you can log a ticket with us for further investigation.
+error is not a LiteSpeed Web Server specific error. If you use a control panel like cPanel, you can try the same steps with Apache. Most likely, Apache will return the same 500 error as LSWS. You will need to find root cause of the problem. If it does not happen to Apache server but only on LSWS, you can [[https://store.litespeedtech.com/store/clientarea.php|log a ticket with us]] for further investigation.
-To troubleshoote 500 error, first to check whether the error affects just one site or every site in the server. Depending on the impact of the error, we debug further. If only one domain it affected, it can be pin-pointed to the specific script error or permission issues. If multiple domains show 500 error, it could be due to some server wide setting change or update.
+To troubleshoot a 500 error, first check whether the error affects just one site or every site in the server. Depending on the impact of the error, you can debug further. If only one domain is affected, it can be pin-pointed to a specific script error or permission issue. If multiple domains show a 500 error, it could be due to some server wide setting change or update.
-You can check server error_log , stderr.log or PHP error-log(normally located where the PHP script running) to see if there is any hint of the error. During the troubleshooting, you may want to ensure PHP error reporting is on in php.ini. Please reverse them back when you done with debuging.
+You can check the server ''error_log'', ''stderr.log'' or PHP error log (normally located where the PHP script is running) to see if there is any hint of the error. During the troubleshooting, you may want to ensure PHP error reporting is on in ''php.ini''. Please reverse the settings back when you're done with debuging.
   error_reporting = E_ALL & ~E_DEPRECATED & ~E_STRICT  ->   error_reporting = E_ALL
   display_errors = Off -> display_errors = On
   display_startup_errors = Off -> display_startup_errors = On
-Please be aware that not all 500 errors log into the logs and it is common that you don’t see any hint in log files, which will make the troubleshooting more difficult then you expected.
+Please be aware that not all 500 errors appear in the logs and it is common not to see any hint in log files This makes troubleshooting more difficult.
-This will list some of the common reasons/examples, which may help you during the troubleshooting processes.
+Here are some of the common reasons/examples, which may help you during the troubleshooting process.
-=====   permission or ownership changes =====
+===== Permission or Ownership Changes =====
- Permission or ownership changes may cause 500 error. For example, to enable LiteMage extension to your Magento installation through ssh, you will need to run as user. However, if you run command incorrectly as the root user, Magento front end may return 500 instantly. The fix is to reverse file ownership and permission back to the original.
+ Permission or ownership changes may cause 500 error.
+ For example, to enable the LiteMage extension in your Magento installation through SSH, you will need to run a a non-root user. However, if you run the command incorrectly as the root user, the Magento front end may return 500 instantly. The fix is to reverse file ownership and permissions back to the original user.
-===== faulty .htaccess =====
+===== phpinfo.php owned by root instead of user =====
-There is a huge range of things .htaccess can do and isn't difficult to use, however, if you do not enter the syntax correctly it can result in a Server 500 Error.
+Sometimes we need to check phpinfo page during the troubleshooting. When ssh login as root to server, go to document root and create phpinfo.php, the phpinfo.php file will be owned by root:root instead of user:user.
+Sometimes it may return 500 error when accessing domain.com/phpinfo.php if some restriction set there but not always.
+The server error may show the following:
+[Thu Jun 07 21:04:36.450359 2018] [:error] [pid 3807521:tid 139749549020928] [client 77.82.94.132:9254] SoftException in Application.cpp:382: UID of script "/home/vivi/public_html/phpBB2/info.php" is smaller than min_uid
+[Thu Jun 07 21:04:36.450651 2018] [core:error] [pid 3807521:tid 139749549020928] [client 77.82.94.132:9254] End of script output before headers: info.php
+Changing the info.php to be owned by user:user will generally fix the issue.
+===== Faulty .htaccess =====
+There is a huge range of things ''.htaccess'' can do and it isn't difficult to use, however, if you do not enter the syntax correctly it can result in a Server 500 Error.
+==== Example 1 ====
 For example,
-  RewriteRule ^(.*) http://www.example.com/$1 [P]  <- wrong , will bring site to 500 error
+  RewriteRule ^(.*) http://www.example.com/$1 [P]
-changed to
+Will cause a 500 error. But change it to
-RewriteRule (.*) http://www.example.com/$1 [R=301,L]   <- will fix the issue
+  RewriteRule (.*) http://www.example.com/$1 [R=301,L]
-To confirm whether a misconfiguration .htaccess is the cause of the 500 Internal Server error, either remove or rename the .htaccess file temporarily and then try to reload the page.
+and that will fix the issue.
+==== Example 2 ====
+<Directory>...</Directory > can not be used in .htacess and it will cause 500 error for Apache, While LSWS will ignore the unsupported directive instead of giving 500 error.
+For example, the following should not be used in .htaccess.
+  <Directory /home/user1/public_html/wp-admin/>
+    Deny from all
+  </Directory>
+instead, you can create .htaccess under /wp-admin/ and place diretive there.
+  Deny from all
+To confirm whether a misconfiguration in ''.htaccess'' is the cause of the 500 Internal Server error, either remove or rename the .htaccess file temporarily and then try to reload the page.
+==== Example 3 ====
+The following "Alias" directive in .htaccess will cause 500 on Apache (LSWS will ignore it without returning 500) since "Alias" directive is not allowed in .htaccess.
+  Alias "/" "/home/$USER1/public_html/"
+==== Example 4 ====
+Syntax is wrong for the followintg directive:
+  Header always set Strict-Transport-Security: max-age=63072000; includeSubDomains; preload
+which will lead to "Too many arguments to directive" error in error_log:
+  [Tue Sep 11 19:59:40.864917 2018] [core:alert] [pid 15738] [client 66.666.76.139:64740] /home/example/public_html/.htaccess: Too many arguments to directive
+The correct syntax is the following and it should fix the 500 error for Apache:
+  Header always set Strict-Transport-Security: "max-age=63072000; includeSubDomains; preload"
+==== Example 5 ====
+Syntax wrong for the following:
+  Options All –Indexes
+It should be:
+  Options -Indexes
+==== Example 6 ====
+''php_value'' and ''php_flag'' are for mod_php handler. Most of the time php-fpm or lsphp will be used and mod_php has been deprecated most of the time. When you use ''php_value'' or ''php_flag'', Apache will return 500 error. However, lsphp supports php override in .htaccess without any problem and there is no 500 error when running LSWS.
+===== Different level of Rewrite rules misplaced to the wrong level =====
+Per virtual host rewrite rules (rewrite rules in Apache virtual host configuration) and per directory rewrite rules (rewrite rules in .htaccess) are different.  When placing the same rules to the wrong place, it may cause 500 error.
+For example, the following works in .htaccess:
+  RewriteEngine On
+  RewriteCond %{REQUEST_FILENAME} !-f
+  RewriteRule . /index.php [L]
+Putting the same thing in Apache VirtualHost config doesn’t work at all:
+  <VirtualHost *:80>
+    ServerName example.com
+    DocumentRoot /var/www/example/
+    <Directory /var/www/example/>
+        Allow From All
+    </Directory>
+    RewriteEngine On
+    RewriteCond %{REQUEST_FILENAME} !-f
+    RewriteRule . /index.php [L]
+  </VirtualHost>
+Apache doesn’t tell you why it doesn’t work. It just doesn’t work. You most likely will get an Error 500 status with a message in the logs that looks like this:
+Request exceeded the limit of 10 internal redirects due to probable configuration error. Use ‘LimitInternalRecursion’ to increase the limit if necessary. Use ‘LogLevel debug’ to get a backtrace.
+===== Incorrect Rewrite Rules misplace in differernt directories =====
+The following rewrite rules in subfolder is incorrect and it will cause 500 for LiteSpeed.
+/home/user1/public_html/subfolder1] vi .htaccess
+  RewriteEngine On
+  RewriteCond %{REQUEST_FILENAME} !-f
+  RewriteCond %{REQUEST_FILENAME} !-d
+  RewriteRule ^(.*)$ subfolder1/index.php/$1 [L]
+The correct rule should be:
+/home/user1/public_html/subfolder1] vi .htaccess
+  RewriteEngine On
+  RewriteCond %{REQUEST_FILENAME} !-f
+  RewriteCond %{REQUEST_FILENAME} !-d
+  RewriteRule ^(.*)$ index.php/$1 [L]
+=====  Improperly Configured php.ini =====
+An improperly configured ''php.ini'' may lead to 500 error.
+For example, set the following in ''php.ini'':
+  open_basedir = "/path/to/folder"
+If the ''/path/to/folder'' directory does not exist, it will cause a 500 error.
-=====  Improperly configured php.ini =====
+===== Bad PHP Code =====
-Improperly configured php.ini may lead to 500 error.
+Bad PHP code will bring a website to 500 immediately.
-For example, set the following in php.ini
- open_basedir = "/path/to/folder"
-However /path/to/folder directory does not exist at all in the system, it will cause 500 error.
-===== Bad PHP code =====
+For example, the right syntax should be:
-Bad php code will bring website to 500 immediately.
-For example, right syntax should be like:
    $this->getResponse()->setRedirect(Mage::getBaseUrl()) ;
-If “$” is removed somehow:
+If the “$” is removed somehow:
     this->getResponse()->setRedirect(Mage::getBaseUrl()) ;
-It will bring website to 500 immediately.
+It will bring the website to 500 immediately.
-This is only one of the examples. Many times, wrong syntax PHP error will lead to 500 error.
+This is only one example. Many times, wrong PHP syntax will lead to a 500 error.
-===== PHP handler not set =====
+Another example is:
-On Plesk, PHP handler not set , prompt 500 error
+  <?php
+  phpinfo():
+  ?>
-===== CloudLinux LVE limit reached =====
+A typing error '':'' in phpinfo page , which should be '';'', will lead to 500 error.
-When using CloudLinux, If the site is limited by memory or number of processes limits, then the user may receive 500 errors that server cannot execute the script.
-https://docs.cloudlinux.com/index.html?lve.html
+===== PHP Code with wrong php configuration settings =====
-===== PHP upgrade =====
+Sometimes, a 500 error may be not easy to locate. If you move ''.htaccess'' to ''.htaccess.bak'' and move ''php.ini'' to ''php.ini.bak'', and the 500 error still happens, it might mean there is something wrong in the PHP code. That can be hard to find.
-Sometimes PHP upgrade with bug may cause 500 error.
-===== Unsupport version of PHP =====
+We experienced a case with WHMCS. Someone placed an incorrect setting in ''configuration.php'':
-unsupport php version by the site/theme/plugin/module may lead to 500 error.
+  $display_errors = E_All;
+''E_All'' is an incorrect value for the PHP ''$display_errors'' setting. Rather, it is meant for the ''$error_reporting'' setting. ''$display_errors'' should be either ''true''/''false'', or ''on''/''off''. We changed it to ''true'', and that fixed the 500 error.
+  $display_errors = true;
-===== PHP coding timing out =====
+===== PHP Handler Not Set =====
-If your PHP script makes external network connections, the connections may time out. If too many connections are attempted and time out, this will cause a "500 Internal Server Error." To prevent these time outs and errors, you'll want to make sure that PHP scripts be coded with some timeout rules. Typically, however, catching a timeout error when connecting to a database or externally to remote resources are difficult. They, in effect, freeze the script from continuing to run.
+On Plesk, if a PHP handler is not set, it will prompt a 500 error.
-===== SYNTAX OR CODING ERRORS IN YOUR CGI/PERL SCRIPT =====
+===== CloudLinux LVE Limit Reached =====
-If it is a web page ending in .cgi or .pl that is producing the error, check your script for errors.
+When using CloudLinux, If the site is limited by memory or process limits, then the user may receive 500 errors because the server cannot execute the script. [[https://docs.cloudlinux.com/index.html?lve.html| Learn more.]]
-===== Run out of Memory on php.ini =====
+For example,  you might see some error like the following:
-check stderr,
- tail /var/log/httpd/stderr.log
--03-01 12:07:03.573 [STDERR] Tue Mar  1 12:07:03 2016 (12700): Fatal Error Unable to allocate shared memory segment of 134217728 bytes: shmat: Cannot allocate memory (12)
+-01-11 00:14:23.330946 [ERROR] [APVH_xsrvnecw_Sulsphp56:]: Failed to start one instance. Resource limit reached!
-Further check phpinfo page and memory limit was set to “128M” only.  While opcode cache sonsution is “128M”.
+The above indicates an Error by Cloudlinux. Increasing the LVE for that user may fix the issue.
-Which leads to 500 error.
-Increate php memory limit from “128M” to 1024M” then fix the issue.
+===== PHP Upgrade =====
+Sometimes if PHP upgrades with a bug, it may cause a 500 error.
+===== Unsupported Version of PHP =====
+Unsupported PHP version used by the site/theme/plugin/module may lead to a 500 error.
-===== too many php processes =====
+===== PHP Scripts Time out =====
-If too many processes in the server queue, it could exceed resources and lead to 500 error.
+If your PHP script makes external network connections, the connections may time out. If too many connections are attempted and time out, this will cause a "500 Internal Server Error." To prevent these time outs and errors, make sure that PHP scripts are coded with some timeout rules. Typically, it's difficult to catch a timeout error when connecting to a database or remote resources, as they effectively freeze the script.
-===== PHP open_basedir may cause 500 error =====
+===== Syntax or Coding Errors in Your CGI/Perl Script =====
-When php open_basedir enabled, it may lead to 500 error.  Try to turn off open_basedir for that domain to see how it is going.
+If it is a web page ending in ''.cgi'' or ''.pl'' that is producing the error, check your script for errors.
-The following error log captured with openlitespeed when PHP open_basedir intentionally set to a non-exist folder /111, phpinfo page returns 500 error.
+===== Out of Memory in php.ini =====
+In this example, we checked ''stderr'':
+  tail /var/log/httpd/stderr.log
--05-16 10:59:51.391153 [NOTICE] [192.168.0.198:14271] [STDERR] PHP Warning:  Unknown: open_basedir restriction in effect. File(/usr/local/lsws/Example/html/phpinfo.php) is not within the allowed path(s): (/111) in Unknown on line 0
+-03-01 12:07:03.573 [STDERR] Tue Mar  1 12:07:03 2016 (12700): Fatal Error Unable to allocate shared memory segment of 134217728 bytes: shmat: Cannot allocate memory (12)
--05-16 10:59:51.391251 [NOTICE] [192.168.0.198:14271] [STDERR] PHP Warning:  Unknown: failed to open stream: Operation not permitted in Unknown on line 0
--05-16 10:59:51.391263 [NOTICE] [192.168.0.198:14271] [STDERR] PHP Fatal error:  Unknown: Failed opening required '/usr/local/lsws/Example/html/phpinfo.php' (include_path='.:/usr/local/lib/php') in Unknown on line 0
-===== apache run as SuEXEC while LSWS not on cpanel =====
-On a cpanel/WHM environment, apache runs as SuEXEC , however LSWS doesn’t.
--03-10 15:39:45.601 [NOTICE] [173.245.52.237:51548] [STDERR] PHP Warning: require_once(/home/demowebsites/public_html/goodmail/wp-config.php): failed to open stream: Permission denied in /home/demowebsites/public_html/goodmail/wp-load.php on line 37
+We further checked the phpinfo page and found the memory limit was set to “128M” only. Opcode cache solution is “128M” by itself, and so there is no memory left for anything else. This leads to a 500 error.
--03-10 15:39:45.601 [NOTICE] [173.245.52.237:51548] [STDERR] PHP Fatal error: require_once(): Failed opening required '/home/demowebsites/public_html/goodmail/wp-config.php' (include_path='.:/opt/cpanel/ea-php70/root/usr/share/pear') in /home/demowebsites/public_html/goodmail/wp-load.php on line 37
-Need to keep LSWS to the same setting to apache. Enabled LSWS PHP SuEXEC and fixed the issue.
+Increase the PHP memory limit from “128M” to 1024M” to fix the issue.
- =====  Run out of swap space =====
+===== Too Many PHP Processes ==
+If there are too many processes in the server queue, it could exceed resources and lead to a 500 error.
-Check error.log, it shows: "Failed to obtain or reinitialize VMemBuf. possibly running out of swap space” and return 500 error. Relocating LSWS swap directory to a partition with enough space will fix the issue.
+===== Apache Running as SuEXEC while LSWS not on cPanel =====
+In a cPanel/WHM environment, Apache runs as SuEXEC, however LSWS doesn’t.
-===== Missing php packages =====
+-03-10 15:39:45.601 [NOTICE] [173.245.52.237:51548] [STDERR] PHP Warning: require_once(/home/demowebsites/public_html/goodmail/wp-config.php): failed to open stream: Permission denied in /home/demowebsites/public_html/goodmail/wp-load.php on line 37
-Install prestashop but 500 returns in Chrome. Check error log and it shows php70-json package missing. Install the missing packages and 500 is gone.
+-03-10 15:39:45.601 [NOTICE] [173.245.52.237:51548] [STDERR] PHP Fatal error: require_once(): Failed opening required '/home/demowebsites/public_html/goodmail/wp-config.php' (include_path='.:/opt/cpanel/ea-php70/root/usr/share/pear') in /home/demowebsites/public_html/goodmail/wp-load.php on line 37
-===== missing opcode cache module =====
+It is necessary to keep LSWS set the same as Apache. Enable LSWS PHP SuEXEC to fix the issue.
-A wordpress site returned 500 error when using go2pay, but there is no hint in server error_log, stderr.log or PHP error_log. Upgrading php version and adding opcode cache module fix the issue. Some applications or plugins may need opcode cache to run.
-===== PHP module code complicting =====
+=====  Run Out of Swap Space =====
-Then run magento, it returns 500 error and show module conflicting
-a:5:{i:0;s:54:"Mage registry key "umm_top_menu_exists" already exists";i:1;s:4439:"#0 /home/yourhome/public_html/app/Mage.php(223): Mage::throwException('Mage registry k...')
+Checking ''error.log'' shows:
- #1 /home/yourhome/public_html/app/design/frontend/ultimo/default/template/infortis/ultramegamenu/mainmenu.phtml(54): Mage::register('umm_top_menu_ex...', true)
+  Failed to obtain or reinitialize VMemBuf. possibly running out of swap space
- #2 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Template.php(241): include('/home/furnishyo...')
- #3 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Template.php(272): Mage_Core_Block_Template->fetchView('frontend/ultimo...')
+error is returned. Relocating the LSWS swap directory to a partition with enough space will fix the issue.
- #4 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Template.php(286): Mage_Core_Block_Template->renderView()
- #5 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Abstract.php(923): Mage_Core_Block_Template->_toHtml()
+===== Missing PHP Packages =====
- #6 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Text/List.php(43): Mage_Core_Block_Abstract->toHtml()
+Installing PrestaShop returns a 500 error in Chrome. Check the error log and it shows ''php70-json'' package is missing. Install the missing packages and the 500 error is gone.
- #7 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Abstract.php(923): Mage_Core_Block_Text_List->_toHtml()
- #8 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Abstract.php(641): Mage_Core_Block_Abstract->toHtml()
+===== Missing Opcode Cache Module =====
- #9 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Abstract.php(585): Mage_Core_Block_Abstract->_getChildHtml('topMenu', true)
+A WordPress site returns a 500 error when using go2pay, but there is no hint in the server ''error_log'', ''stderr.log'' or PHP ''error_log''. Upgrading the PHP version and adding the opcode cache module fixes the issue. Some applications or plugins may need opcode cache to run.
+===== PHP Module Code Conflicting =====
+Magento returns a 500 error and shows a module conflict.
+  a:5:{i:0;s:54:"Mage registry key "umm_top_menu_exists" already exists";i:1;s:4439:"#0 /home/yourhome/public_html/app/Mage.php(223): Mage::throwException('Mage registry k...')
+  #1 /home/yourhome/public_html/app/design/frontend/ultimo/default/template/infortis/ultramegamenu/mainmenu.phtml(54): Mage::register('umm_top_menu_ex...', true)
+  #2 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Template.php(241): include('/home/furnishyo...')
+  #3 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Template.php(272): Mage_Core_Block_Template->fetchView('frontend/ultimo...')
+  #4 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Template.php(286): Mage_Core_Block_Template->renderView()
+  #5 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Abstract.php(923): Mage_Core_Block_Template->_toHtml()
+  #6 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Text/List.php(43): Mage_Core_Block_Abstract->toHtml()
+  #7 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Abstract.php(923): Mage_Core_Block_Text_List->_toHtml()
+  #8 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Abstract.php(641): Mage_Core_Block_Abstract->toHtml()
+  #9 /home/yourhome/public_html/app/code/core/Mage/Core/Block/Abstract.php(585): Mage_Core_Block_Abstract->_getChildHtml('topMenu', true)
+===== Disable/Enable Some Magento Modules =====
+When disabling ''extendare_EWCore.xml'' by changing from “True” to “false, it shows a 500 error.
+Remove Magento cache files and fix the problem:
-===== disabling/enable some magento modules =====
-When disabling extendare_EWCore.xml by changing from “True” to “false, it shows 500 error.
-Remove magento cache files and fix the problem.
   rm -rf var/cache/*
-===== some mod security rules may cause 500 error =====
+===== Some mod_security Rules May Cause a 500 Error =====
-Add java script to a wordpress plugin, but it causes 500 error. Enable LSWS debug logging and found:
+Adding Javascript to a WordPress plugin causes a 500 error. Enable LSWS debug logging and find:
+<code>
 -05-12 04:13:16.673307 [NOTICE] [47.22.54.182:54823#APVH_latampolitics.carinsurancegeorgia.org] mod_security rule [Id '2000145'] triggered! [Sat May 12 04:13:16 2018] [error] [client 47.22.54.182] ModSecurity: Access denied with code 500, [Rule: 'REQUEST_URI|REQUEST_BODY' '<space:(script|about|applet|activex|chrome) >.(script|about|applet|activex|chrome)space: >'] [id "2000145"] [rev "1"] [msg "xss"] [severity "CRITICAL"]
+</code>
+A mod_security rule lead to the 500 error. Disable that mod_security rule to fix the issue.
+===== Hacked Site =====
+If your site is being hacked, it may trigger a 500 error.
+===== Perl script missing "Content-Type" header may return 500 =====
+Run a simple "Hello World" perl script at http://exmaple.com/cgi-bin/test.pl but it return 500 error.
+vi test.pl
+<code>
+  #!/usr/bin/perl
+  print "Hello, World!\n";
+</code>
+A Perl CGI script must output the header, HTML code and also must begin with a special first line. In this case, header "Content-type" is missing and it is not a CGI script. Please also be aware that there is a blank line after **print "Content-Type: text/html\n\n";**.
+the right script should be:
+<code>
+<code>
+  #!/usr/bin/perl
+  print "Content-Type: text/html\n\n";
+  print "Hello, World!\n";
+</code>
+You can check the example [[https://users.cs.cf.ac.uk/Dave.Marshall/PERL/node196.html|here]].
+===== OWASP ModSecurity rule set may trigger 500 when using Imunify360 together =====
+If you use LSWS ealier than 5.4.1 build 7, you may see 500 error when both OWASP and Imunify360 used at the same time. LSWS 5.4.1 and above version should have fixed this issue and LiteSpeed user can use both rule sets at the same time.
+OWASP rule set may conflict with the Imunify360 default rule set on a server running LiteSpeed Web Server. Please choose only one mod_security rule set.
+For OWASP rulesets, in crs-setup.conf:
+  SecAction "id:900990, phase:1, nolog, pass, t:none, setvar:tx.crs_setup_version=302"
+in /etc/apache2/conf.d/modsec_vendor_configs/OWASP3/rules/REQUEST-901-INITIALIZATION.conf
+  SecRule &TX:crs_setup_version "@eq 0" "id:901001, phase:1, auditlog, log, deny, status:500, severity:CRITICAL, msg:'ModSecurity Core Rule Set is deployed without configuration! Please copy the crs-setup.conf.example template to crs-setup.conf, and include the crs-setup.conf file in your webserver configuration before including the CRS rules. See the INSTALL file in the CRS directory for detailed instructions.'"
+crs-setup.conf has to be loaded first then the rest of rules including REQUEST-901-INITIALIZATION.conf.
+Imunify360 could break the loading order of the above rule set and lead to "500" errors.
+===== Use Debug Logging to find out the real cause =====
-Mod_security rule leads to 500 error.  Try to disable that mod security rule and fix the issue.
+To Toggle Debug Logging, and capture the logs, you can use the following guide -
+https://www.litespeedtech.com/support/wiki/doku.php/litespeed_wiki:config:bug-reporting#how_to_toggle_debug_logging_and_capture_output
-===== hacked site =====
+These logs can be further investigated, or you can forward them to our Support Team.
-If your site is being hacked, it may trigger 500 error.