[ consider your addon domain name as addondomain.com ]
There are 3 ways of accessing an addon domain:
1. addondomain.com
2. main-domain.com/addondomain
3. addondomain.main-domain.com

Parked Domain :: A parked domain is one which simply points to an existing domain. It is an other domain which is parked on to the main domain. Consider a domain “parked.com” which is parked on the “main-domain.com”. If we access parked.com it will be directed to the main-domain.com and you will get the same page as you see while accessing main-domain.com. The parked domain should also point to the same nameservers as the main-domain.com. The park domain name should be registered.

Make sure the Name servers for the othersite.com (addon OR parked) has the same Name servers registered that of main site.

Create a .htaccess file under the root directory and add the code below

Redirect www.domain.com to domain.com

Options +FollowSymLinks
RewriteEngine On
RewriteCond %{HTTP_HOST} ^www.domain\.com$ [NC]
RewriteRule ^(.*)$ http://domain.com/$1 [R=301,L]

Redirect domain.com to www.domain.com

Options +FollowSymLinks
RewriteEngine On
RewriteCond %{HTTP_HOST} ^domain\.com$ [NC]
RewriteRule ^(.*)$ http://domain.com/$1 [R=301,L]

Save the file and exit and give it a try once

Login to WHM with root user and access the option Server Configuration >> Tweak Settings. Look for MySQL and check the radio button for 5.0 from 4.1 OR login to the server via SSH and open the file /var/cpanel/cpanel.config and find for mysql-version. Change it to 5.0 from 4.1. Save the file and exit. Now execute the commands on the server to upgrade the mysql version.

/scripts/upcp –force

/scripts/mysqlup –force

Wait for mysql to upgrade. Once the process is completed, check the mysql version.

For non suexec/suphp servers

Create a .htaccess file under the diretcory and add the code below

php_flag short_open_tag X

For suexec/suphp servers

Copy the server’s php.ini file under the diretcory and find for short_open_tag. Open the php.ini file and change it to

short_open_tag = X

Note :: The solution is valid only if you find the error due to line in your php/html file.
HTML Code:

<?xml version=”1.0″ encoding=”iso-8859-1″?>
OR
<?xml version=”1.0″ encoding=”UTF-8″?>

Check emails in mail queue

root@server [~]# exim -bp

Count number of emails in mail queue

root@server [~]# exim -bpc

Count number of frozen emails in mail queue

root@server [~]# exim -bp | grep frozen | wc -l

Delete forzen emails from the mail queue

exim -bp | awk ‘$6~”frozen” { print $3 }’ | xargs exim -Mrm

Count emails for an email account/domain

exim -bp | grep  username@domain.com | wc -l

Delete emails for an email account

exim -bp | grep  username@domain.com  | awk ‘{print $3}’ | xargs exim -Mrm ;

Delete emails sent through scripts

exim -bp | grep “<>” | awk {‘print $3}’ | xargs exim -Mrm

Count number of emails in queue for a domain/email account

exim -bp | tr ‘\n’ + | sed -e “s/++/=/g” | tr -d + | tr = ‘\n’ | awk ‘{print $5}’ | sort -n | uniq -c | sort -n

Delete emails for root

exim -bp | grep  root@server.hostname.com  | awk ‘{print $3}’ | xargs exim -Mrm ;

Hope this helps to troubleshoot mail issues on the server

If you are on a su-exec/su-php enabled server, copy the original php.ini from the server under the account and make the changes.

What is output_buffering ?

Output buffering allows you to send header lines (including cookies) even
after you send body content, at the price of slowing PHP’s output layer a
bit.  You can enable output buffering during runtime by calling the output
buffering functions.  You can also enable output buffering for all files by
setting this directive to On.  If you wish to limit the size of the buffer
to a certain size – you can use a maximum number of bytes instead of ‘On’, as
a value for this directive (e.g., output_buffering=4096).

Here is the command to exclude/skip home diretcory

root@server [~]# /scripts/pkgacct –skiphomedir username

Note :: Here username is  actual cPanel username.

You can disable .htaccess for a particular domain by editing the /etc/httpd/conf/httpd.conf file & following the below mentioned steps:

Open the /etc/httpd/conf/httpd.conf file.
Search for the “AllowOverride None” string.

<Directory “/”>
AllowOverride None
</Directory>

Append it by:

<Directory “/home/username/public_html”>
AllowOverride None
</Directory>

Such that it looks like:

<Directory “/”>
AllowOverride None
</Directory>

<Directory “/home/username/public_html”>
AllowOverride None
</Directory>

Restart the httpd/apache service on the server

This would disable the .htaccess for that particular account/domain.

Change permissions for the diretcory “cart/images/uploads” to 777

Change permissionsfor diretcory “cart/images/uploads/thumbs” to 777.

You are done ! Try uploading the images now.