diff --git a/src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/caching/ShadowJarCachingTest.kt b/src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/caching/ShadowJarCachingTest.kt
index f8ef875cc..cc72bf4aa 100644
--- a/src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/caching/ShadowJarCachingTest.kt
+++ b/src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/caching/ShadowJarCachingTest.kt
@@ -10,7 +10,6 @@ import kotlin.io.path.appendText
 import kotlin.io.path.readText
 import kotlin.io.path.writeText
 import org.gradle.api.file.DuplicatesStrategy
-import org.junit.jupiter.api.Disabled
 import org.junit.jupiter.api.Test
 
 class ShadowJarCachingTest : BaseCachingTest() {
@@ -211,7 +210,6 @@ class ShadowJarCachingTest : BaseCachingTest() {
     }
   }
 
-  @Disabled("TODO: https://github.com/GradleUp/shadow/pull/1601#discussion_r2260096815")
   @Test
   fun shadowJarIsCachedCorrectlyAfterApplicationChanged() {
     val mainClassName = "my.Main"
diff --git a/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowApplicationPlugin.kt b/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowApplicationPlugin.kt
index 72d362abc..a6d6743d6 100644
--- a/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowApplicationPlugin.kt
+++ b/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/ShadowApplicationPlugin.kt
@@ -127,16 +127,18 @@ public abstract class ShadowApplicationPlugin : Plugin<Project> {
   }
 
   protected open fun Project.configureShadowJarMainClass() {
-    val mainClassName = applicationExtension.mainClass
+    // Default to empty string to avoid the error of the value not being configured yet.
+    val mainClassName = applicationExtension.mainClass.convention("")
     tasks.shadowJar.configure { task ->
+      task.inputs.property("mainClassName", mainClassName)
       task.doFirst {
         // Inject the attribute if it is not already present.
         if (!task.manifest.attributes.contains(mainClassAttributeKey)) {
-          task.manifest.attributes[mainClassAttributeKey] = mainClassName.orNull.also { value ->
-            if (value.isNullOrEmpty()) {
-              error("The main class must be specified and not left empty in `application.mainClass` or manifest attributes.")
-            }
+          val realClass = mainClassName.orNull
+          if (realClass.isNullOrEmpty()) {
+            error("The main class must be specified and not left empty in `application.mainClass` or manifest attributes.")
           }
+          task.manifest.attributes[mainClassAttributeKey] = realClass
         }
       }
     }