I successfully install Apache Tomcat 9 and I access at servername:8080.
I follow documentation in order to access the manager web app and :
<role rolename="manager-gui"/>
<user username="tomcat" password="s3cret" roles="manager-gui"/>
I can't find what config I am missing and will be greateful for any kind of help or suggestion.
I wanto to share the solution I found here not in the marked answer but in the fade's answer.
Commenting the Valve attribute in CATALINA_HOME/webapps/manager/META-INF/context.xml and restarting Tomcat solve the problem and I can now assess the web manager