Hi @dmanibabu ,
Where are you trying to create this launcher, is it in your local or other environment ?
Please got o your network tab in browser dev console and see if there is any n/w call happening for launcher like "/libs/cq/workflow/launcher" and it should give 200 for successful call.
If its throwing 500 then there is something wrong with your server.
Also, validate if there are any other launcher created under path "/conf/global/settings/workflow/launcher/config". Try to check if you are able to create in your local instance.
-Tarun