When performing a migration from another billing system or WHMCS installation, we recommend using our ImportAssist addon, which supports importing data from multiple billing systems. At this time, this supports the following systems:

The above URL is more about moving WHMCS to another server. Moving WHMCS into a subdomain in the same overall site file area shouldn’t be much work. You need to basically:

1. Move the WHMCS files into the new location, or set the subdomain path to the subdirectory already containing the WHMCMS files.

2. Reissue your license at whmcs.com so it will pick up the new location.

3. Access the admin area and change the URLs in Setup -> General Settings.

4. Check configuration.php and update any paths that might need updated if you use $templates_compiledir, $attachments_dir, $downloads_dir (though if you do you probably are pointing to paths outside of the web root that won’t be affected by the WHMCS move.)

5. If you have any hardcoded links in your WHMCS theme (you shouldn’t but you never know) update them with the new URLs. (Or better, make them properly relative.)

6. If you have clients with paypal subscriptions, the IPN notification URL is fixed in the subscription, so create a mod_rewrite rule to make sure the IPNs post to the new location:

RewriteRule ^modules/gateways/callback/paypal.php$ https:///client.myhost.com/gateways/callback/paypal.php [L,NC]

(Put this rule in the .htaccess file in the original WHMCS location, not the new location.)

My Data collection source:

I think that’s about it. We did this about a month ago and to my recollection those are the only things we had to do.

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I got all the Infromation from https://whmcs.community/topic/184801-how-to-moving-whmcs-to-sub-domain/ub-domain/

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