The problem is in ServerInfo.properties
I was just attempting to add an Apache Tomcat server to Eclipse Java EE IDE for Web Developers, Version: Mars.2, when I ran into a nasty snag: In the New Server dialog, the Next> button is not enabled. I also noticed an error in the top of the dialog: “The Apache Tomcat installation at this directory is version 8.5.15. A Tomcat 8.0 installation is expected“. Very annoying.
After some searching I found out that the problem is in ServerInfo.properties. The server.info= line needs to have the value: Apache Tomcat/8.0.0.
The above screenshot shows the issue. So if you run into this problem, this Stack Overflow article: How to use Tomcat 8.5.x and TomEE 7.x with Eclipse? – Stack Overflow has the answer you need. Check out the answer by dexter-meyers. But also note the edit by informatik01. In short, you want to follow the detailed steps to patch catalina.jar, but you only need to change the version in the server.info= line.
For the complete answer to this issue, check out this Stack Overflow page: