I am trying to put script in the head of the pages of my site , I am getting 403 error

description of the error -
Uncaught Error: Sys.WebForms.PageRequestManagerServerErrorException: An unknown error occurred while processing the request on the server. The status code returned from the server was: 403


Please see -
# When we are submitting head without putting script tag , and putting something else it is submitted , but with head tag it is not submitted

# I is happening on all the page of my site