Resolved [org.springframework.web.bind.MissingServletRequestParameterException: Required long parameter 'pageNo' is not present]

The `Resolved [org.springframework.web.bind.MissingServletRequestParameterException: Required long parameter 'pageNo' is not present]` is an error message thrown by the Spring Framework when it encounters a missing required request parameter during web request handling. In this case, the error specifically relates to a parameter named `pageNo`, which is expected to be a long value (an integer) but is not found in the incoming HTTP request.

Here's a breakdown of what it means:

1. **Cause:** The issue arises when you have a method or controller action in your Spring application that is annotated with `@RequestParam` or some other annotation expecting a `pageNo` as a parameter, and this parameter is marked as `required=true`. The framework is looking for this parameter in the URL query string or request body, but it's not present.

2. **Solution:**
- **Check the request**: Make sure you've included the `pageNo` parameter in the correct format, either in the URL as `?pageNo=value` (query string) or in the request body (if you're using POST/PUT).
- **Validation configuration:** If the parameter is supposed to be optional, ensure that the validation annotations (`@RequestParam(required = false)` or similar) are set correctly.
- **Handle exceptions:** Use Spring's exception handling mechanism, such as `@ExceptionHandler(MissingServletRequestParameterException.class)`, to provide a default response or a more user-friendly error message.