diff --git a/README.md b/README.md
index 1780efd4215..fd1b8dee22d 100644
--- a/README.md
+++ b/README.md
@@ -10,36 +10,21 @@ It supports numerous game systems, most notably:
 - Starfinder
 
 # Table of Contents
-1. [Installing From Release 6.08](#installing-from-release-608)
+1. [Installing PCGen](#installing-pcgen)
 
-2. [Installing From Release 6.09 (Alpha)](#installing-from-release-609-alpha)
+2. [PCGen Needs You](#pcgen-needs-you)
 
-3. [PCGen Needs You](#pcgen-needs-you)
+3. [The Old Wiki](#the-old-wiki)
 
-4. [The Old Wiki](#the-old-wiki)
+4. [PCGen LST Tutorial](#pcgen-lst-tutorial)
 
-5. [PCGen LST Tutorial](#pcgen-lst-tutorial)
+5. [Basic Workflow](#basic-workflow)
 
-6. [Basic Workflow](#basic-workflow)
+6. [Development Setup](#development-setup)
 
-7. [Development Setup](#development-setup)
+7. [Essential Gradle Tasks](#essential-gradle-tasks)
 
-8. [Essential Gradle Tasks](#essential-gradle-tasks)
-
-# Installing From Release 6.08
-1. Install Java.
-   - JDK 11 is recommended and has long term support, later versions should also work. 10 and below are not supported.
-   - To check if you have Java installed, see [Install Java](#install-java)
-   - If you don't have it already, you can get it from [Eclipse Temurin](https://adoptium.net/temurin/releases/?version=11).
-   
-2. Download and extract the full zip file from https://github.com/PCGen/pcgen/releases/latest.
-
-3. You should now be able to run PCGen. The exact invocation depends on your operating system, but you should be able to either double-click to launch the file for your platform.
-    - Windows: `pcgen.exe` (`pcgen.bat` for command-line users)
-    - Linux: `pcgen.sh` 
-    - Mac: `pcgen.jar` (or `pcgen.dmg` if it exists)
-    
-# Installing From Release 6.09 (Alpha)
+# Installing PCGen
 > Note: Java does not need to be preinstalled with PcGen >6.09.05
 
 ## Using Zip bundle
@@ -111,8 +96,7 @@ Check the installed version with:
 
     java -version
 
-For 6.08 development you will want Java with a minimum version of 11.
-For 6.09 development you will want Java with a minimum version of 25.
+For development you will want Java with a minimum version of 25.
 You can install the latest version from [Eclipse Temurin](https://adoptium.net) regardless of your OS, please see instructions there.
 
 ### Install Git
diff --git a/build.gradle b/build.gradle
index b1975b0711e..0970f8b4531 100644
--- a/build.gradle
+++ b/build.gradle
@@ -79,6 +79,36 @@ java {
     }
 }
 
+// Replace Gradle's opaque toolchain error with an actionable message.
+gradle.taskGraph.whenReady { graph ->
+    def needsCompile = graph.allTasks.any { it instanceof JavaCompile }
+    if (!needsCompile) return
+
+    try {
+        javaToolchains.launcherFor(java.toolchain).get()
+    } catch (Exception e) {
+        throw new GradleException("""
+
+            PCGen requires JDK ${javaVersion} to build, but Gradle could not
+            find one on this machine.
+
+            Currently running: Java ${System.getProperty('java.version')}
+                               at ${System.getProperty('java.home')}
+
+            Install JDK ${javaVersion} (or newer) and either:
+              - Set JAVA_HOME to it, or
+              - Run: ./gradlew -Porg.gradle.java.installations.paths=<path-to-jdk-${javaVersion}> <task>
+
+            Verify Gradle can see it:  ./gradlew -q javaToolchains
+
+            Downloads:
+              - Adoptium Temurin: https://adoptium.net/temurin/releases/?version=${javaVersion}
+              - Azul Zulu:        https://www.azul.com/downloads/?version=java-${javaVersion}-lts
+              - SapMachine:       https://sapmachine.io/
+            """.stripIndent(), e)
+    }
+}
+
 application {
     mainClass.set('pcgen.system.Main')
 }