'''Issue:''' Browsers implement security checks, such as verifying the CORS headers in the server response, to ensure the requested domain is allowed. If the server is on a different domain, the browser checks if the requesting domain is whitelisted in the CORS headers. For example, if you're sending a request from the domain '[https://fescobilling.pk/xyz]' to a server hosted on '[https://pescobilling.pk/abc]', the browser will verify that the xyz server has whitelisted the abc domain or IP. '''Solution:''' To resolve this issue, you'll need to request the server's technical team to whitelist your domain. Alternatively, you can consume the APIs from a server-side language instead.