Sorry, me again, peppering you with problems... So, as mentioned, I got my converted Grails 7 app to run fine with './gradlew bootRun'. So I thought I'd try deploying a .war to Tomcat and this is very odd! Basically nothing happens. The .war is correctly expanded, and it appears to go through the process of deployment: 24-Jul-2025 181357.851 INFO [main] org.apache.catalina.startup.HostConfig.deployWAR Deploying web application archive [/opt/tomcat/webapps/socialsupermarket.war] 24-Jul-2025 181358.309 WARNING [main] org.apache.tomcat.util.descriptor.web.WebXml.setVersion Unknown version string [5.0]. Default version will be used. 24-Jul-2025 181358.357 WARNING [main] org.apache.tomcat.util.descriptor.web.WebXml.setVersion Unknown version string [6.0]. Default version will be used. 24-Jul-2025 181358.375 WARNING [main] org.apache.tomcat.util.descriptor.web.WebXml.setVersion Unknown version string [6.0]. Default version will be used. 24-Jul-2025 181402.506 INFO [main] org.apache.jasper.servlet.TldScanner.scanJars At least one JAR was scanned for TLDs yet contained no TLDs. Enable debug logging for this logger for a complete list of JARs that were scanned but no TLDs were found in them. Skipping unneeded JARs during scanning can improve startup time and JSP compilation time. 24-Jul-2025 181402.606 INFO [main] org.apache.catalina.startup.HostConfig.deployWAR Deployment of web application archive [/opt/tomcat/webapps/socialsupermarket.war] has finished in [4,754] ms But nothing is actually deployed. The web app is not running, and no errors are written to the log explaining why not. (There should be dozens of lines before the deployment has finished line). The configuration of the .war is unchanged from 6.2.3: bootWar { enabled = false } war { enabled = true archiveBaseName.set('socialsupermarket') archiveVersion.set('') archiveClassifier.set('') } Any ideas?

Believe Tomcat 10 is required b/c of the API changes, @James Fredley would know more about this though. I personally use embedded undertow

That makes sense. Assuming Tomcat 10 will run Grails 6 apps OK (with Java 17), I will see if I can upgrade. Or I may go down the embedded Undertow approach, which I have done in a few other places.

@James Fredley is far more familiar with this than I am. He will know

Thinking about it, the same change which makes Tomcat 10 mandatory for Grails 7 will make it unusable for Grails 6, I assume (the replacement of 'javax' with 'jakarta').

https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-dependencies/3.5.3 is the quickest way to find the right tomcat version for Grails 7 https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-dependencies/2.7.18 for Grails 6.2.x https://docs.grails.org/snapshot/ref/Versions/Grails%20BOM.html also exists staring with Grails 7

Just as a FYI, I did a quick test and the app does in fact run fine with an embedded server, which is Tomcat 10 (although I thought I had specified Undertow, need to check out why that might be).