Note -> Please take backup before applying patch
Step 1: Download the patch, as shown in the screenshot below ,according to your WHMCS version.
Step 2: Now from local go to the patch folder that you have extracted.
Step 3: Now navigate to the path shown below in the screenshot on both local (extracted file root path ) and server (whmcs root path).
Step 4: After extracting the Patch go to the path as shown in the screenshot (\order\ -> In local ) and (/order-> In server ) to upload the “order” files.
Note : Please keep the backup of the existing folder in your local. Then start uploading process
Step 5: Now navigate to the path shown below in the screenshot on both local and server for “vueWhmcsCart” addon files. (\whmcs\modules\addons\ -> In local ) and (/modules/addons-> In server ) to upload the “vueWhmcsCart” addon module files.

Step 6. Now Drag/upload the file to upload addons patch files and override files screenshot given below.
Step 7. Now Drag/upload the file to upload “api” folder files and override files screenshot given below.

Step 8. Now Drag/upload the file to upload “lib” folder file and override files screenshot given below.
Step 9. Now Drag/upload the file to upload “pages” folder file and override files screenshot given below.