When you have an issue like this on extension manager try some work around mentioned below
A. WORKAROUND to access Activation Records:
► Accessing the Activation Record via URL:
– https://<ACCOUNT_ID>.app.netsuite.com/app/site/hosting/scriptlet.nl?script=<SCRIPT_ID>&deploy=1&compid=<ACCOUNT_ID>&service_name=STEP_2&website_id=<WEBSITE_ID>&domain_id=<CUSTOMER_DOMAIN>&subsidiary_id=&location_id=
B.WORKAROUND to create new Activation Record:
► If new activation is needed, access new Activation page thru this link:
– https://<ACCOUNT_ID>.app.netsuite.com/app/site/hosting/scriptlet.nl?script=<SCRIPT_ID>&deploy=1&compid=<ACCOUNT_ID>&whence=&service_name=STEP_1
NOTE:
– <ACCOUNT_ID>: Customer Account ID
– <SCRIPT_ID>: Script ID of “NS SC ExtMechanism Services” SuiteLet
– <CUSTOMER_DOMAIN>: This is the customer domain associated to a website record. (e.g. www.mywebstore.com)
– <WEBSITE_ID>: Website Record ID (Make sure to replace this with the exact website ID of the customer domain)