APACHE TROUBLESHOOTING TIPS

ISSUE # 1 :- This site can’t be reached Or Unable to connect

• Possibly Apache down. Pidof httpd
• Restart Apache service >> stop & start
• netstat -plane |grep :80 >> to confirm whether apache is running
• Check whether apache conf syntax is correcthttpd configtest

• Check Apache log >> find out the error message and trouble the issue according to the error message.

ISSUE # 2 :- 500 Internal Server Error

• tail -f /usr/local/apache/log/error_log |grep USER >> user level
• tail -f /usr/local/apache/log/error_log >> server level
• Check .htaccess rewrite rules

ISSUE # 3 :- 500 error >> Blank Page

• Check whether the size of index page is zero bytes
• Correct files and folder ownership and permission

• Check error_log in application.

• If client uses php based application >> Enable php display_errors and refresh the site again >> trouble shoot the issue based on the error message.
• Find the name of application installed in the site and search how to enable display_errors/debug mode/error notice for that particular application.
• Rename modules/plugin folders and then refresh the page (F5 ) >> if its working, find out the problematic module/plugin
• Change application theme/template
• Check LMD event log
• Check .htaccess rewrite rules

ISSUE # 4 :- 404 Not Found

• Check whether the requested resource or contents exist in the path.
• Check whether the user type in the wrong URL
• Does the file exist in the correct location on the server? Was the resource was moved or deleted on the server?
• Check whether the domain have correct DocumentRoot; check the apache config.
• Check the ownership and permission of the file/folder.
• Check whether the resource being accessed a symbolic link.
• Check if there is any .htaccess file and rewrite rules.
• Some CMS application’s resource calls from database, so you have to check the .htaccess has proper rewrite rules (permalink).

ISSUE # 5 :- 403 Forbidden Permission Denied

• Check whether the domain has proper index page.
• Check ownership and permission of files/folders
• Check ownership and permission of /, /home, /home/user, /home/user/public_html
• Check the domain’s vhost entries especially DocumentRoot in apache conf.
• Check .htaccess file in the DocumentRoot and rewrite rules

ISSUE # 6 :- 401 Unauthorized

• Check .htaccess and confirm that whether HTTP authentication is correct.

ISSUE # 7 :- 502 Bad Gateway

• Check whether the reverse proxy is configured properly.
• Check if the server has any additional proxy servers configured. Like nginx, varnish etc.

ISSUE # 8 :- 503 Service Unavailable

• Probably this kind of error codes are directly related to CPU and Memory Usage.
• In CloudLinux server, check Virtual memory, physical memory, CPU, number of entry processes limit, I/O limits etc..

ISSUE # 9 :- 508 Resource Limit Is Reached

• In a CloudLinux installed server, each account has a predefined amount of resources. So check Virtual memory, physical memory, CPU, number of entry processes limit, I/O limits etc..

ISSUE # 10 :- 406 Error – Not Acceptable

• This error code is mod_security related. So check apache logs,

grep USER /usr/local/apache/logs/error_log
ISSUE # 11 :- 504 Gateway Timeout

• Check proxy server configuration.

ISSUE # 12 :- 509 Bandwidth Limit Exceeded

• The server has exceeded the bandwidth specified by the server administrator. Check the BW usage of the domain.

ISSUE # 13 :- Error 310 (net::ERR_TOO_MANY_REDIRECTS)

• Check the .htaccess file located in public_html or /home/User/
• Rename modules/plugins folder
• Check if there is any redirection specified in the index page.

ISSUE # 14 :- Apache: No space left on device: Couldn’t create accept lock

• Apache shows as running, but unable to connect web server port. When we error logs, we can see error message like “No space left on device: Couldn’t create accept lock”.
• There are many reasons behind this error,

1. Apache Semaphore:
           ipcs -s
For killing semaphore processes,
       for i in `ipcs -s | awk ‘/nobody/ {print $2}’`; do (ipcrm -s $i); done
     2. Check your disk space
     3. Review file system quotas
ISSUE # 15:- Apache downloads php files instead of displaying them
PHP handler issue.

• Check .htaccess contents in the path of /home/User, Domain’s DocumentRoot
• Check php handler value in domain’s virtual host or apache conf
• 
  

ISSUE # 16 :- Domain Shows Apache Default Page

• DNS and Apache IP address conflict. Check whether the DNS A record and Apache Vhost IP are same.
• Check domain’s Vhost entries.