Note -> Please take backup before applying patch
Step 1: Download the patch, as shown in the screenshot below, according to your WHMCS version.
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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 (\whmcs_dir\modules\addons\ -> In local ) and (/modules/addons-> In server ) to upload the “adminx” addon module.

Step 5: Now navigate to the path shown below in the screenshot on both local and server for adminx template file, (whmcs_dir\admin\templates\adminx\ -> In local ) and (/admin/templates/adminx -> In server ). For adminx template files.

Step 6. Now Drag/upload the file to upload admin template patch file and override files screenshot given below.