v4.5.1 Bug Fix Released

• IF ENVIRONMENT is in Development on Localhost, why we need HTTPS?
  

If  HTTPS  is must for secure request in localhost (development stage), how can i use the serverSide enabled datatable?
Also how to create SSL Certificate for codeIgniter 4 (installed from composer) on localhost.

Help me to solve this

In this context, "Secure" means HTTPS.
I don't think you need HTTPS on localhost development environment.
But you configured to use Secure Cookie. So CI4 throws the security exception.

Your choices are:
1. do not use secure cookie in development environment (and use HTTP)
2. install SSL Certificate (and web server) in your localhost (and use HTTPS)

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