IntelliJ ignoring project SDK and using the wrong Java version

I know how to set the project SDK, and that's set to JDK 1.7, but when my app runs it appears to be using JDK 1.8.

Furthermore, InteliJ seems to start with the right JVM.

However, after a few seconds of running it presents an endless series of errors like this, which you would expect if it was using Java 1.8 as described in this answer: Incompatible JVM in GGTS (Eclipse) and JAVA 1.8

Oct 27, 2020 11:46:17 AM org.springsource.loaded.jvm.JVM copyMethod
SEVERE: Problems copying method. Incompatible JVM?
java.lang.reflect.InvocationTargetException
    at sun.reflect.GeneratedMethodAccessor75.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.springsource.loaded.jvm.JVM.copyMethod(JVM.java:134)
    at org.springsource.loaded.ri.OriginalClassInvoker.createJavaMethod(OriginalClassInvoker.java:68)
    at org.springsource.loaded.ri.ReflectiveInterceptor.jlClassGetDeclaredMethods(ReflectiveInterceptor.java:151)
    at org.codehaus.groovy.grails.commons.ClassPropertyFetcher.init(ClassPropertyFetcher.java:181)
    at org.codehaus.groovy.grails.commons.ClassPropertyFetcher.<init>(ClassPropertyFetcher.java:91)
    at org.codehaus.groovy.grails.commons.ClassPropertyFetcher.forClass(ClassPropertyFetcher.java:82)
    at org.codehaus.groovy.grails.commons.ClassPropertyFetcher.forClass(ClassPropertyFetcher.java:63)
    at org.codehaus.groovy.grails.commons.AbstractGrailsClass.<init>(AbstractGrailsClass.java:84)
    at org.codehaus.groovy.grails.plugins.AbstractGrailsPlugin$GrailsPluginClass.<init>(AbstractGrailsPlugin.java:65)
    at org.codehaus.groovy.grails.plugins.DefaultGrailsPlugin.initialisePlugin(DefaultGrailsPlugin.java:138)
    at org.codehaus.groovy.grails.plugins.DefaultGrailsPlugin.<init>(DefaultGrailsPlugin.java:117)
    at org.codehaus.groovy.grails.plugins.DefaultGrailsPlugin.<init>(DefaultGrailsPlugin.java:264)
    at org.codehaus.groovy.grails.plugins.DefaultGrailsPluginManager.createGrailsPlugin(DefaultGrailsPluginManager.java:411)
    at org.codehaus.groovy.grails.plugins.DefaultGrailsPluginManager.findUserPlugins(DefaultGrailsPluginManager.java:436)
    at org.codehaus.groovy.grails.plugins.DefaultGrailsPluginManager.attemptLoadPlugins(DefaultGrailsPluginManager.java:348)
    at org.codehaus.groovy.grails.plugins.DefaultGrailsPluginManager.loadPlugins(DefaultGrailsPluginManager.java:256)
    at org.codehaus.groovy.grails.project.plugins.GrailsProjectPluginLoader$_loadPlugins_closure2.doCall(GrailsProjectPluginLoader.groovy:103)
    at org.codehaus.groovy.grails.project.plugins.GrailsProjectPluginLoader$_loadPlugins_closure2.call(GrailsProjectPluginLoader.groovy)
    at org.codehaus.groovy.grails.cli.api.BaseSettingsApi.profile(BaseSettingsApi.java:342)
    at org.codehaus.groovy.grails.project.plugins.GrailsProjectPluginLoader.loadPlugins(GrailsProjectPluginLoader.groovy:99)
    at org.codehaus.groovy.grails.plugins.GrailsPluginManagerFactoryBean.afterPropertiesSet(GrailsPluginManagerFactoryBean.java:75)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1613)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1550)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:539)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:302)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:298)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)

Solution

Turns out the default version of Java I configured to 1.8 with sdkman was setting with the value of JAVA_HOME that my app was using. I just needed to override the value in my run configuration.

Run > Edit Configurations...