Give up on trying to upgrade users past 6.7.0

Author: pichfl

src/constants.js

@@ -7,3 +7,5 @@ module.exports.defaultAddonBlueprintName = 'addon';
 module.exports.glimmerPackageName = '@glimmer/blueprint';
 
 module.exports.defaultTo = '*';
+
+module.exports.EMBER_LEGACY_BLUEPRINT_VERSION = '6.7.0';

src/index.js

@@ -20,8 +20,13 @@ const getBaseBlueprint = require('./get-base-blueprint');
 const chooseBlueprintUpdates = require('./choose-blueprint-updates');
 const getBlueprintFilePath = require('./get-blueprint-file-path');
 const resolvePackage = require('./resolve-package');
-const { defaultTo } = require('./constants');
+const {
+  defaultTo,
+  defaultAppBlueprintName,
+  EMBER_LEGACY_BLUEPRINT_VERSION
+} = require('./constants');
 const normalizeBlueprintArgs = require('./normalize-blueprint-args');
+const semver = require('semver');
 
 /**
  * If `version` attribute exists in the `blueprint` object and URL is empty, skip. Otherwise resolve the details of
@@ -211,6 +216,15 @@ module.exports = async function emberCliUpdate({
         let versions = await getVersions(packageName);
         let getTagVersion = _getTagVersion(versions, packageName);
         endBlueprint.version = await getTagVersion(to);
+
+        if (
+          packageName === defaultAppBlueprintName &&
+          semver.gt(endBlueprint.version, EMBER_LEGACY_BLUEPRINT_VERSION)
+        ) {
+          throw new Error(
+            `you cannot use ember-cli-update to automatically upgrade past ${EMBER_LEGACY_BLUEPRINT_VERSION}. Read the following documentation to find out how to proceed <link to somewhere> `
+          );
+        }
       }
 
       let customDiffOptions = getStartAndEndCommands({