diff --git a/packages/metro/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js b/packages/metro/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js
index c759f858..1e7aa3a5 100644
--- a/packages/metro/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js
+++ b/packages/metro/src/DeltaBundler/__tests__/traverseDependencies-integration-test.js
@@ -52,6 +52,7 @@ describe('traverseDependencies', function() {
   let traverseDependencies;
   let defaults;
   let emptyTransformOptions;
+  let UnableToResolveError;
 
   async function getOrderedDependenciesAsJSON(
     dgraphPromise,
@@ -95,6 +96,9 @@ describe('traverseDependencies', function() {
 
     Module = require('../../node-haste/Module');
     traverseDependencies = require('../traverseDependencies');
+    ({
+      UnableToResolveError,
+    } = require('../../node-haste/DependencyGraph/ModuleResolution'));
 
     emptyTransformOptions = {transformer: {transform: {}}};
     defaults = {
@@ -1024,7 +1028,11 @@ describe('traverseDependencies', function() {
           await getOrderedDependenciesAsJSON(dgraph, '/root/index.js');
           throw new Error('should be unreachable');
         } catch (error) {
-          expect(error.type).toEqual('UnableToResolveError');
+          if (!(error instanceof UnableToResolveError)) {
+            throw error;
+          }
+          expect(error.originModulePath).toBe('/root/index.js');
+          expect(error.targetModuleName).toBe('lolomg');
         }
       });
     });
@@ -2972,7 +2980,11 @@ describe('traverseDependencies', function() {
           await getOrderedDependenciesAsJSON(dgraph, '/root/index.js');
           throw new Error('should be unreachable');
         } catch (error) {
-          expect(error.type).toEqual('UnableToResolveError');
+          if (!(error instanceof UnableToResolveError)) {
+            throw error;
+          }
+          expect(error.originModulePath).toBe('/root/index.js');
+          expect(error.targetModuleName).toBe('dontWork');
         }
         filesystem.root['index.js'] = filesystem.root['index.js']
           .replace('require("dontWork")', '')
@@ -3394,6 +3406,8 @@ describe('traverseDependencies', function() {
   describe('node_modules (win32)', function() {
     let DependencyGraph;
     let processDgraph;
+    let UnableToResolveError;
+
     beforeEach(() => {
       Object.defineProperty(process, 'platform', {
         configurable: true,
@@ -3406,6 +3420,9 @@ describe('traverseDependencies', function() {
       jest.mock('path', () => require.requireActual('path').win32);
       DependencyGraph = require('../../node-haste/DependencyGraph');
       processDgraph = processDgraphFor.bind(null, DependencyGraph);
+      ({
+        UnableToResolveError,
+      } = require('../../node-haste/DependencyGraph/ModuleResolution'));
     });
 
     it('should work with nested node_modules', async () => {
@@ -3879,7 +3896,11 @@ describe('traverseDependencies', function() {
           await getOrderedDependenciesAsJSON(dgraph, entryPath);
           throw new Error('should be unreachable');
         } catch (error) {
-          expect(error.type).toEqual('UnableToResolveError');
+          if (!(error instanceof UnableToResolveError)) {
+            throw error;
+          }
+          expect(error.originModulePath).toBe('C:\\root\\index.js');
+          expect(error.targetModuleName).toBe('dontWork');
         }
         filesystem.root['index.js'] = filesystem.root['index.js']
           .replace('require("dontWork")', '')
@@ -4381,7 +4402,6 @@ describe('traverseDependencies', function() {
     });
 
     it('updates module dependencies on file delete', async () => {
-      expect.assertions(1);
       var root = '/root';
       var filesystem = setMockFileSystem({
         root: {
@@ -4418,7 +4438,11 @@ describe('traverseDependencies', function() {
           await getOrderedDependenciesAsJSON(dgraph, '/root/index.js');
           throw new Error('should be unreachable');
         } catch (error) {
-          expect(error.type).toEqual('UnableToResolveError');
+          if (!(error instanceof UnableToResolveError)) {
+            throw error;
+          }
+          expect(error.originModulePath).toBe('/root/index.js');
+          expect(error.targetModuleName).toBe('foo');
         }
       });
     });
@@ -4527,7 +4551,11 @@ describe('traverseDependencies', function() {
           await getOrderedDependenciesAsJSON(dgraph, entryPath);
           throw new Error('should be unreachable');
         } catch (error) {
-          expect(error.type).toEqual('UnableToResolveError');
+          if (!(error instanceof UnableToResolveError)) {
+            throw error;
+          }
+          expect(error.originModulePath).toBe('/root/index.js');
+          expect(error.targetModuleName).toBe('./foo.png');
         }
         filesystem.root['foo.png'] = '';
         await triggerAndProcessWatchEvent(dgraph, 'change', root + '/foo.png');
@@ -5006,7 +5034,11 @@ describe('traverseDependencies', function() {
           await getOrderedDependenciesAsJSON(dgraph, '/root/index.jsx');
           throw Error('should be unreachable');
         } catch (error) {
-          expect(error.type).toEqual('UnableToResolveError');
+          if (!(error instanceof UnableToResolveError)) {
+            throw error;
+          }
+          expect(error.originModulePath).toBe('/root/index.jsx');
+          expect(error.targetModuleName).toBe('./a');
         }
       });
     });
diff --git a/packages/metro/src/lib/formatBundlingError.js b/packages/metro/src/lib/formatBundlingError.js
index 9a1a7028..84ebba78 100644
--- a/packages/metro/src/lib/formatBundlingError.js
+++ b/packages/metro/src/lib/formatBundlingError.js
@@ -12,6 +12,9 @@
 
 'use strict';
 
+const {
+  UnableToResolveError,
+} = require('../node-haste/DependencyGraph/ModuleResolution');
 const {
   AmbiguousModuleResolutionError,
 } = require('../node-haste/DependencyGraph/ResolutionRequest');
@@ -52,10 +55,9 @@ function formatBundlingError(
   }
 
   if (
-    error instanceof Error &&
-    (error.type === 'TransformError' ||
-      error.type === 'NotFoundError' ||
-      error.type === 'UnableToResolveError')
+    error instanceof UnableToResolveError ||
+    (error instanceof Error &&
+      (error.type === 'TransformError' || error.type === 'NotFoundError'))
   ) {
     error.errors = [
       {
diff --git a/packages/metro/src/node-haste/DependencyGraph/ModuleResolution.js b/packages/metro/src/node-haste/DependencyGraph/ModuleResolution.js
index 7c668de4..012507ea 100644
--- a/packages/metro/src/node-haste/DependencyGraph/ModuleResolution.js
+++ b/packages/metro/src/node-haste/DependencyGraph/ModuleResolution.js
@@ -112,7 +112,7 @@ function tryResolveSync<T>(action: () => T, secondaryAction: () => T): T {
   try {
     return action();
   } catch (error) {
-    if (error.type !== 'UnableToResolveError') {
+    if (!(error instanceof UnableToResolveError)) {
       throw error;
     }
     return secondaryAction();
@@ -189,7 +189,7 @@ class ModuleResolver<TModule: Moduleish, TPackage: Packageish> {
     }
 
     throw new UnableToResolveError(
-      fromModule,
+      fromModule.path,
       toModuleName,
       'Unable to resolve dependency',
     );
@@ -290,7 +290,7 @@ class ModuleResolver<TModule: Moduleish, TPackage: Packageish> {
 
     const hint = displaySearchQueue.length ? ' or in these directories:' : '';
     throw new UnableToResolveError(
-      fromModule,
+      fromModule.path,
       toModuleName,
       `Module does not exist in the module map${hint}\n` +
         displaySearchQueue
@@ -328,7 +328,7 @@ class ModuleResolver<TModule: Moduleish, TPackage: Packageish> {
     const {dir} = result.candidates;
     if (dir.type === 'package') {
       throw new UnableToResolveError(
-        fromModule,
+        fromModule.path,
         toModuleName,
         `could not resolve \`${potentialModulePath}' as a folder: it ` +
           'contained a package, but its "main" could not be resolved',
@@ -336,7 +336,7 @@ class ModuleResolver<TModule: Moduleish, TPackage: Packageish> {
     }
     invariant(dir.type === 'index', 'invalid candidate type');
     throw new UnableToResolveError(
-      fromModule,
+      fromModule.path,
       toModuleName,
       `could not resolve \`${potentialModulePath}' as a file nor as a folder`,
     );
@@ -472,7 +472,7 @@ class ModuleResolver<TModule: Moduleish, TPackage: Packageish> {
       return module;
     }
     throw new UnableToResolveError(
-      fromModule,
+      fromModule.path,
       toModuleName,
       "could not resolve `${ModuleResolver.EMPTY_MODULE}'",
     );
@@ -583,22 +583,31 @@ function failedFor<TModule, TCandidates>(
   return {type: 'failed', candidates};
 }
 
-class UnableToResolveError<TModule: Moduleish> extends Error {
-  type: string;
-  from: string;
-  to: string;
+class UnableToResolveError extends Error {
+  /**
+   * File path of the module that tried to require a module, ex. `/js/foo.js`.
+   */
+  originModulePath: string;
+  /**
+   * The name of the module that was required, no necessarily a path,
+   * ex. `./bar`, or `invariant`.
+   */
+  targetModuleName: string;
 
-  constructor(fromModule: TModule, toModule: string, message: string) {
+  constructor(
+    originModulePath: string,
+    targetModuleName: string,
+    message: string,
+  ) {
     super();
-    this.from = fromModule.path;
-    this.to = toModule;
+    this.originModulePath = originModulePath;
+    this.targetModuleName = targetModuleName;
     this.message = util.format(
       'Unable to resolve module `%s` from `%s`: %s',
-      toModule,
-      fromModule.path,
+      targetModuleName,
+      originModulePath,
       message,
     );
-    this.type = this.name = 'UnableToResolveError';
   }
 }