diff --git a/packages/docusaurus-plugin-content-blog/src/__tests__/pluginOptionSchema.test.ts b/packages/docusaurus-plugin-content-blog/src/__tests__/pluginOptionSchema.test.ts
index 3f85ded47c..9697a1417e 100644
--- a/packages/docusaurus-plugin-content-blog/src/__tests__/pluginOptionSchema.test.ts
+++ b/packages/docusaurus-plugin-content-blog/src/__tests__/pluginOptionSchema.test.ts
@@ -7,12 +7,14 @@
 
 import {PluginOptionSchema, DEFAULT_OPTIONS} from '../pluginOptionSchema';
 
-// the type of remark/rehype plugins is function
-const remarkRehypePluginStub = () => {};
+// the type of remark/rehype plugins can be either function, object or array
+const markdownPluginsFunctionStub = () => {};
+const markdownPluginsObjectStub = {};
 
 test('should normalize options', () => {
-  const {value} = PluginOptionSchema.validate({});
+  const {value, error} = PluginOptionSchema.validate({});
   expect(value).toEqual(DEFAULT_OPTIONS);
+  expect(error).toBe(undefined);
 });
 
 test('should accept correctly defined user options', () => {
@@ -24,27 +26,29 @@ test('should accept correctly defined user options', () => {
     postsPerPage: 5,
     include: ['api/*', 'docs/*'],
   };
-  const {value} = PluginOptionSchema.validate(userOptions);
+  const {value, error} = PluginOptionSchema.validate(userOptions);
   expect(value).toEqual({
     ...userOptions,
     feedOptions: {type: ['rss'], title: 'myTitle'},
   });
+  expect(error).toBe(undefined);
 });
 
 test('should accept valid user options', async () => {
   const userOptions = {
     ...DEFAULT_OPTIONS,
-    routebasePath: '',
+    routeBasePath: '',
     beforeDefaultRemarkPlugins: [],
-    beforeDefaultRehypePlugins: [remarkRehypePluginStub],
-    remarkPlugins: [remarkRehypePluginStub, {option1: '42'}],
+    beforeDefaultRehypePlugins: [markdownPluginsFunctionStub],
+    remarkPlugins: [[markdownPluginsFunctionStub, {option1: '42'}]],
     rehypePlugins: [
-      remarkRehypePluginStub,
-      [remarkRehypePluginStub, {option1: '42'}],
+      markdownPluginsObjectStub,
+      [markdownPluginsFunctionStub, {option1: '42'}],
     ],
   };
-  const {value} = await PluginOptionSchema.validate(userOptions);
+  const {value, error} = await PluginOptionSchema.validate(userOptions);
   expect(value).toEqual(userOptions);
+  expect(error).toBe(undefined);
 });
 
 test('should throw Error in case of invalid options', () => {
diff --git a/packages/docusaurus-plugin-content-blog/src/pluginOptionSchema.ts b/packages/docusaurus-plugin-content-blog/src/pluginOptionSchema.ts
index d3605c1d97..466271253d 100644
--- a/packages/docusaurus-plugin-content-blog/src/pluginOptionSchema.ts
+++ b/packages/docusaurus-plugin-content-blog/src/pluginOptionSchema.ts
@@ -58,22 +58,12 @@ export const PluginOptionSchema = Joi.object({
   admonitions: AdmonitionsSchema.default(DEFAULT_OPTIONS.admonitions),
   editUrl: URISchema,
   truncateMarker: Joi.object().default(DEFAULT_OPTIONS.truncateMarker),
-  beforeDefaultRemarkPlugins: Joi.array()
-    .items(
-      Joi.array()
-        .items(Joi.function().required(), Joi.object().required())
-        .length(2),
-      Joi.function(),
-    )
-    .default(DEFAULT_OPTIONS.beforeDefaultRemarkPlugins),
-  beforeDefaultRehypePlugins: Joi.array()
-    .items(
-      Joi.array()
-        .items(Joi.function().required(), Joi.object().required())
-        .length(2),
-      Joi.function(),
-    )
-    .default(DEFAULT_OPTIONS.beforeDefaultRehypePlugins),
+  beforeDefaultRemarkPlugins: RemarkPluginsSchema.default(
+    DEFAULT_OPTIONS.beforeDefaultRemarkPlugins,
+  ),
+  beforeDefaultRehypePlugins: RehypePluginsSchema.default(
+    DEFAULT_OPTIONS.beforeDefaultRehypePlugins,
+  ),
   feedOptions: Joi.object({
     type: Joi.alternatives().conditional(
       Joi.string().equal('all', 'rss', 'atom'),
diff --git a/packages/docusaurus-plugin-content-docs/src/__tests__/pluginOptionSchema.test.ts b/packages/docusaurus-plugin-content-docs/src/__tests__/pluginOptionSchema.test.ts
index 08ddaf7f1f..4fb4304ff0 100644
--- a/packages/docusaurus-plugin-content-docs/src/__tests__/pluginOptionSchema.test.ts
+++ b/packages/docusaurus-plugin-content-docs/src/__tests__/pluginOptionSchema.test.ts
@@ -9,12 +9,14 @@ import {PluginOptionSchema, DEFAULT_OPTIONS} from '../pluginOptionSchema';
 import {normalizePluginOptions} from '@docusaurus/utils-validation';
 
 // the type of remark/rehype plugins is function
-const remarkRehypePluginStub = () => {};
+const markdownPluginsFunctionStub = () => {};
+const markdownPluginsObjectStub = {};
 
 describe('normalizeDocsPluginOptions', () => {
   test('should return default options for undefined user options', async () => {
-    const {value} = await PluginOptionSchema.validate({});
+    const {value, error} = await PluginOptionSchema.validate({});
     expect(value).toEqual(DEFAULT_OPTIONS);
+    expect(error).toBe(undefined);
   });
 
   test('should accept correctly defined user options', async () => {
@@ -26,29 +28,57 @@ describe('normalizeDocsPluginOptions', () => {
       sidebarPath: 'my-sidebar', // Path to sidebar configuration for showing a list of markdown pages.
       docLayoutComponent: '@theme/DocPage',
       docItemComponent: '@theme/DocItem',
-      remarkPlugins: [],
-      rehypePlugins: [remarkRehypePluginStub],
+      remarkPlugins: [markdownPluginsObjectStub],
+      rehypePlugins: [markdownPluginsFunctionStub],
       showLastUpdateTime: true,
       showLastUpdateAuthor: true,
       admonitions: {},
       excludeNextVersionDocs: true,
       disableVersioning: true,
     };
-    const {value} = await PluginOptionSchema.validate(userOptions);
+    const {value, error} = await PluginOptionSchema.validate(userOptions);
     expect(value).toEqual(userOptions);
+    expect(error).toBe(undefined);
   });
 
   test('should accept correctly defined remark and rehype plugin options', async () => {
     const userOptions = {
       ...DEFAULT_OPTIONS,
-      remarkPlugins: [remarkRehypePluginStub, {option1: '42'}],
+      remarkPlugins: [[markdownPluginsFunctionStub, {option1: '42'}]],
       rehypePlugins: [
-        remarkRehypePluginStub,
-        [remarkRehypePluginStub, {option1: '42'}],
+        markdownPluginsObjectStub,
+        [markdownPluginsFunctionStub, {option1: '42'}],
       ],
     };
-    const {value} = await PluginOptionSchema.validate(userOptions);
+    const {value, error} = await PluginOptionSchema.validate(userOptions);
     expect(value).toEqual(userOptions);
+    expect(error).toBe(undefined);
+  });
+
+  test('should reject invalid remark plugin options', () => {
+    expect(() => {
+      normalizePluginOptions(PluginOptionSchema, {
+        remarkPlugins: [[{option1: '42'}, markdownPluginsFunctionStub]],
+      });
+    }).toThrowErrorMatchingInlineSnapshot(
+      `"\\"remarkPlugins[0]\\" does not match any of the allowed types"`,
+    );
+  });
+
+  test('should reject invalid rehype plugin options', () => {
+    expect(() => {
+      normalizePluginOptions(PluginOptionSchema, {
+        rehypePlugins: [
+          [
+            markdownPluginsFunctionStub,
+            {option1: '42'},
+            markdownPluginsFunctionStub,
+          ],
+        ],
+      });
+    }).toThrowErrorMatchingInlineSnapshot(
+      `"\\"rehypePlugins[0]\\" does not match any of the allowed types"`,
+    );
   });
 
   test('should reject bad path inputs', () => {
diff --git a/packages/docusaurus-plugin-content-docs/src/pluginOptionSchema.ts b/packages/docusaurus-plugin-content-docs/src/pluginOptionSchema.ts
index 7e67024a99..7e3a983bd2 100644
--- a/packages/docusaurus-plugin-content-docs/src/pluginOptionSchema.ts
+++ b/packages/docusaurus-plugin-content-docs/src/pluginOptionSchema.ts
@@ -36,7 +36,7 @@ export const PluginOptionSchema = Joi.object({
   routeBasePath: Joi.string().allow('').default(DEFAULT_OPTIONS.routeBasePath),
   homePageId: Joi.string().optional(),
   include: Joi.array().items(Joi.string()).default(DEFAULT_OPTIONS.include),
-  sidebarPath: Joi.string().default(DEFAULT_OPTIONS.sidebarPath),
+  sidebarPath: Joi.string().allow('').default(DEFAULT_OPTIONS.sidebarPath),
   docLayoutComponent: Joi.string().default(DEFAULT_OPTIONS.docLayoutComponent),
   docItemComponent: Joi.string().default(DEFAULT_OPTIONS.docItemComponent),
   remarkPlugins: RemarkPluginsSchema.default(DEFAULT_OPTIONS.remarkPlugins),
diff --git a/packages/docusaurus-utils-validation/src/validationSchemas.ts b/packages/docusaurus-utils-validation/src/validationSchemas.ts
index d6ffd6d692..332a460d08 100644
--- a/packages/docusaurus-utils-validation/src/validationSchemas.ts
+++ b/packages/docusaurus-utils-validation/src/validationSchemas.ts
@@ -13,11 +13,9 @@ export const PluginIdSchema = Joi.string()
 
 const MarkdownPluginsSchema = Joi.array()
   .items(
-    Joi.array()
-      // TODO, this allows [config,fn] too?
-      .items(Joi.function().required(), Joi.object().required())
-      .length(2),
+    Joi.array().ordered(Joi.function().required(), Joi.object().required()),
     Joi.function(),
+    Joi.object(),
   )
   .default([]);
 
diff --git a/packages/docusaurus/package.json b/packages/docusaurus/package.json
index 67f803841c..12a3e0561d 100644
--- a/packages/docusaurus/package.json
+++ b/packages/docusaurus/package.json
@@ -107,8 +107,7 @@
     "webpack-bundle-analyzer": "^3.6.1",
     "webpack-dev-server": "^3.11.0",
     "webpack-merge": "^4.2.2",
-    "webpackbar": "^4.0.0",
-    "@docusaurus/utils-validation": "^2.0.0-alpha.61"
+    "webpackbar": "^4.0.0"
   },
   "peerDependencies": {
     "react": "^16.8.4",