What is causing the error in the console?

Question

PHP

Hello. Please tell me what could be causing the error?
Warning: mysqli_num_rows() expects parameter 1 to be mysqli_result, boolean given

Answer 1

With the fact that there is an error in the request
Before connecting to the database, there should always be a line

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);

and then php will tell you which one

Answer 2

Translate the error and you will understand.
You send a bool to mysqli_num_rows (probably false), not mysqli_result (probably false was returned to you when you requested, not a cursor)