Solved

I mean, the information are quite vague. I’m not sure how the db setting comes into play in your mind. But based on your exception I did a quick search in the tomcat-maven-plugin tags and it looks like this is the version you are using: https://github.com/apache/tomcat-maven-plugin/blob/tomcat-maven-plugin-2.0/tomcat7-war-runner/src/main/java/org/apache/tomcat/maven/runner/Tomcat7Runner.java#L526C5-L529C37

One can also see, that the team behind this plugin added a fix for your problem in the 2.1 version https://github.com/apache/tomcat-maven-plugin/blob/tomcat-maven-plugin-2.1/tomcat7-war-runner/src/main/java/org/apache/tomcat/maven/runner/Tomcat7Runner.java#L638C8-L641C10
There they explicitly catch the null case you are encountering.
Based on that I would say you have two options:

  1. Check if you can simply upgrade the dependency for the tomcat-maven-plugin to something newer than 2.0
  2. Follow the code and try to figure out where the value comes from, which is passed on to that method and give it some value. Even “” could help

(PS: I’m not sure if this problem is vaadin related at all)

Solved

@natural-kangaroo In the future, please don’t delete your original question. Now no one else who has a similar question can find it.