under IIS, check if you have the security tool [URLScan] installed or not
UrlScan is a security tool that restricts the types of HTTP requests that Microsoft Internet Information Services (IIS) will process. By blocking specific HTTP requests, the UrlScan security tool helps prevent potentially harmful requests from reaching the server. UrlScan is implemented as an ISAPI filter that screens and analyzes HTTP requests as IIS receives them. When properly configured, UrlScan is effective at reducing the exposure of IIS to potential Internet attacks.