Local File Inclusion

Hello! I need help! A started the FILE INCLUSION / DIRECTORY TRAVERSAL in HTB Academy, and the second site at Local File Inclusion I opened the linked webpage/extension site which add a .php extension to the end of the link. I tried to use the %00 (based on the curriculum) at the and of the passwd but it was not working. I got back this error “Failed opening ‘/etc/passwd’ for inclusion (include_path=‘.:/usr/share/php’) in” I tried to use php file truncation larger than php 4096 bytes but it didn’t work either. Could you help me What do I do wrong?