This message that you are getting normally
comes up when a user modifies the Tab Link name that the Go To Link
action is looking for.
I also wanted to assure you that the CRM_EditCustomer
screen wasn’t deleted because you can see the name in the screen listing.
Try the following steps:
Customize > Tabs
Find the “Customers” tab
Click on Edit Tab Links
Take a look at the Tab Link Name column and see
if the name Edit Customer is still the same
If it is not the same, change it to the steps 4 bolded
name and try the Go To link again
Let me know if that helps.