diff --git a/packages/ember-cli-fastboot/lib/broccoli/html-writer.js b/packages/ember-cli-fastboot/lib/broccoli/html-writer.js
index 07bdff388..f928ade88 100644
--- a/packages/ember-cli-fastboot/lib/broccoli/html-writer.js
+++ b/packages/ember-cli-fastboot/lib/broccoli/html-writer.js
@@ -25,11 +25,13 @@ module.exports = class BasePageWriter extends Filter {
   processString(content) {
     let dom = new JSDOM(content);
     let scriptTags = dom.window.document.querySelectorAll('script');
-
     this._ignoreUnexpectedScripts(scriptTags);
 
     let fastbootScripts = this._findFastbootScriptToInsert(scriptTags);
     let appJsTag = findAppJsTag(scriptTags, this._appJsPath, this._rootURL);
+    if (!appJsTag) {
+      throw new Error('ember-cli-fastboot cannot find own app script tag');
+    }
     insertFastbootScriptsBeforeAppJsTags(fastbootScripts, appJsTag);
 
     return dom.serialize();
@@ -79,6 +81,10 @@ function getRootURL(appName, config) {
 }
 
 function urlWithin(candidate, root) {
+  // this is a null or relative path
+  if (!candidate || !candidate.startsWith('/')) {
+    return candidate;
+  }
   let candidateURL = new URL(candidate, 'http://_the_current_origin_');
   let rootURL = new URL(root, 'http://_the_current_origin_');
   if (candidateURL.href.startsWith(rootURL.href)) {
diff --git a/test-packages/basic-app/test/package-json-test.js b/test-packages/basic-app/test/package-json-test.js
index 0cc69fc81..31c340f3f 100644
--- a/test-packages/basic-app/test/package-json-test.js
+++ b/test-packages/basic-app/test/package-json-test.js
@@ -36,7 +36,7 @@ describe("generating package.json", function () {
     it("contains a schema version", function () {
       let pkg = fs.readJSONSync("dist/package.json");
 
-      expect(pkg.fastboot.schemaVersion).to.deep.equal(3);
+      expect(pkg.fastboot.schemaVersion).to.deep.equal(5);
     });
 
     it("contains a whitelist of allowed module names", function () {
@@ -54,25 +54,6 @@ describe("generating package.json", function () {
       ]);
     });
 
-    it("contains a manifest of FastBoot assets", function () {
-      let pkg = fs.readJSONSync("dist/package.json");
-
-      expect(pkg.fastboot.manifest).to.deep.equal({
-        appFiles: [
-          "assets/basic-app.js",
-          "assets/basic-app-fastboot.js",
-          "example-addon/bar.js",
-        ],
-        htmlFile: "index.html",
-        vendorFiles: [
-          "example-addon/foo.js",
-          "assets/vendor.js",
-          "assets/auto-import-fastboot.js",
-          "ember-fetch/fetch-fastboot.js",
-        ],
-      });
-    });
-
     it("contains a list of whitelisted hosts from environment.js", function () {
       let pkg = fs.readJSONSync("dist/package.json");
 
@@ -86,7 +67,7 @@ describe("generating package.json", function () {
     it("contains app name", function () {
       let pkg = fs.readJSONSync("dist/package.json");
 
-      expect(pkg.fastboot.appName).to.equal("basic-app");
+      expect(pkg.name).to.equal("basic-app");
     });
 
     it("contains the application config", function () {
@@ -132,28 +113,5 @@ describe("generating package.json", function () {
 
       expect(pkg.fastboot.config["foo"]).to.equal("bar");
     });
-
-  });
-
-  describe("with production FastBoot builds", function () {
-    before(async function () {
-      await execa("yarn", ["build", "--environment=production"]);
-    });
-
-    it("contains a manifest of FastBoot assets", function () {
-      let pkg = fs.readJSONSync("dist/package.json");
-
-      let manifest = pkg.fastboot.manifest;
-
-      manifest.appFiles.forEach((file) => {
-        expect(`dist/${file}`).to.be.a.file();
-      });
-
-      expect(`dist/${manifest.htmlFile}`).to.be.a.file();
-
-      manifest.vendorFiles.forEach((file) => {
-        expect(`dist/${file}`).to.be.a.file();
-      });
-    });
   });
 });
diff --git a/test-packages/custom-fastboot-app/public/custom-index.html b/test-packages/custom-fastboot-app/public/custom-index.html
index a21d3d3e3..129015759 100644
--- a/test-packages/custom-fastboot-app/public/custom-index.html
+++ b/test-packages/custom-fastboot-app/public/custom-index.html
@@ -10,12 +10,12 @@
     <!-- EMBER_CLI_FASTBOOT_HEAD -->
 
     <link rel="stylesheet" href="assets/vendor.css">
-    <link rel="stylesheet" href="assets/custom-html-file.css">
+    <link rel="stylesheet" href="assets/custom-fastboot-app.css">
   </head>
   <body>
     <!-- EMBER_CLI_FASTBOOT_BODY -->
 
     <script src="assets/vendor.js"></script>
-    <script src="assets/custom-html-file.js"></script>
+    <script src="assets/custom-fastboot-app.js"></script>
   </body>
 </html>
diff --git a/test-packages/custom-fastboot-app/test/package-json-test.js b/test-packages/custom-fastboot-app/test/package-json-test.js
index 4b0df782c..024fe4b27 100644
--- a/test-packages/custom-fastboot-app/test/package-json-test.js
+++ b/test-packages/custom-fastboot-app/test/package-json-test.js
@@ -52,10 +52,10 @@ describe("generating package.json", function () {
     describe('with custom htmlFile', function() {
       it('uses custom htmlFile in the manifest', function() {
         let pkg = fs.readJSONSync("dist/package.json");
-        let manifest = pkg.fastboot.manifest;
+        let { htmlEntrypoint} = pkg.fastboot;
 
-        expect(manifest.htmlFile).to.equal('custom-index.html');
-        expect(`dist/${manifest.htmlFile}`).to.be.a.file();
+        expect(htmlEntrypoint).to.equal('custom-index.html');
+        expect(`dist/${htmlEntrypoint}`).to.be.a.file();
       });
     });
   });