To resolve that problem, go to phpMyAdmin, and click on the top left "Empty Session Data" icon like the following screenshot. The issue will be settled.
If you are facing an issue of loading react UseEffect twice, then go to your application "src>>index.js" file. You will get the code like the following snippets. Old React Code Remove that old react code by the following snippets. New Code It will solve the issue. Happy coding!
When registering a WordPress custom post type, add 'show_in_rest' => true parameter to the argument. https://developer.wordpress.org/rest-api/extending-the-rest-api/adding-rest-api-support-for-custom-content-types/
You can get a full list of icons from the following link. https://wordpress.github.io/gutenberg/?path=/story/icons-icon--library