diff --git a/src/webui/src/components/Header/index.js b/src/webui/src/components/Header/index.js
index 3426805c1..19d0d95ad 100644
--- a/src/webui/src/components/Header/index.js
+++ b/src/webui/src/components/Header/index.js
@@ -44,7 +44,7 @@ export default class Header extends React.Component {
 
   componentWillMount() {
     API.request('logo')
-    .then((response) => response.text().then((logo) => this.setState({logo})))
+    .then((logo) => this.setState({logo}))
     .catch((error) => {
       throw new Error(error);
     });
@@ -66,13 +66,13 @@ export default class Header extends React.Component {
         username: this.state.username,
         password: this.state.password
       };
-      let resp = await API.request(`login`, 'POST', {
+      const resp = await API.request(`login`, 'POST', {
         body: JSON.stringify(credentials),
         headers: {
           Accept: HEADERS.JSON,
           'Content-Type': HEADERS.JSON
         }
-      }).then((response) => response.json());
+      });
 
       storage.setItem('token', resp.token);
       storage.setItem('username', resp.username);
@@ -80,9 +80,9 @@ export default class Header extends React.Component {
     } catch (e) {
       const errorObj = {
         title: 'Unable to login',
-        type: 'error'
+        type: 'error',
+        description: e.error
       };
-      errorObj.description = e.message;
       this.setState({loginError: errorObj});
     }
   }
diff --git a/src/webui/src/components/PackageSidebar/index.jsx b/src/webui/src/components/PackageSidebar/index.jsx
index 82f535dcb..deed61706 100644
--- a/src/webui/src/components/PackageSidebar/index.jsx
+++ b/src/webui/src/components/PackageSidebar/index.jsx
@@ -33,9 +33,7 @@ export default class PackageSidebar extends React.Component {
     let packageMeta;
 
     try {
-      packageMeta = await API.request(`sidebar/${packageName}`, 'GET').then(function(response) {
-        return response.json();
-      });
+      packageMeta = await API.request(`sidebar/${packageName}`, 'GET');
     } catch (err) {
       this.setState({
         failed: true
diff --git a/src/webui/src/modules/detail/index.jsx b/src/webui/src/modules/detail/index.jsx
index acd93be16..0c305426c 100644
--- a/src/webui/src/modules/detail/index.jsx
+++ b/src/webui/src/modules/detail/index.jsx
@@ -47,7 +47,7 @@ export default class Detail extends React.Component {
     });
 
     try {
-      const resp = await API.request(`package/readme/${packageName}`, 'GET').then((response) => response.text());
+      const resp = await API.request(`package/readme/${packageName}`, 'GET');
       this.setState({
         readMe: resp
       });
diff --git a/src/webui/src/modules/home/index.js b/src/webui/src/modules/home/index.js
index 8160d79f8..72a19879f 100644
--- a/src/webui/src/modules/home/index.js
+++ b/src/webui/src/modules/home/index.js
@@ -51,7 +51,7 @@ export default class Home extends React.Component {
 
   async loadPackages() {
     try {
-      this.req = await API.request('packages', 'GET').then((response) => response.json());
+      this.req = await API.request('packages', 'GET');
 
       if (this.state.query === '') {
         this.setState({
@@ -70,7 +70,7 @@ export default class Home extends React.Component {
 
   async searchPackage(query) {
    try {
-     this.req = await API.request(`/search/${query}`, 'GET').then((response) => response.json());
+     this.req = await API.request(`/search/${query}`, 'GET');
 
      // Implement cancel feature later
      if (this.state.query === query) {
diff --git a/src/webui/utils/api.js b/src/webui/utils/api.js
index c76ffe3e2..fa0436ca4 100644
--- a/src/webui/utils/api.js
+++ b/src/webui/utils/api.js
@@ -17,18 +17,42 @@ class API {
         url = window.VERDACCIO_API_URL + url;
       }
 
-      function handleErrors(response) {
-        if (!response.ok) {
-            throw Error(response.statusText);
+      /**
+       * Handles response according to content type
+       * @param {object} response
+       * @returns {promise}
+       */
+      function handleResponseType(response) {
+        if (response.headers) {
+          const contentType = response.headers.get('Content-Type');
+          if (contentType.includes('application/pdf')) {
+            return Promise.all([response.ok, response.blob()]);
+          }
+          if (contentType.includes('application/json')) {
+            return Promise.all([response.ok, response.json()]);
+          }
+          // it includes all text types
+          if (contentType.includes('text/')) {
+            return Promise.all([response.ok, response.text()]);
+          }
         }
-        return response;
       }
 
-      return fetch(url, {
-        method,
-        credentials: 'same-origin',
-        ...options
-      }).then(handleErrors);
+      return new Promise((resolve, reject) => {
+        fetch(url, {
+          method,
+          credentials: 'same-origin',
+          ...options
+        })
+        .then(handleResponseType)
+        .then(([responseOk, body]) => {
+          if (responseOk) {
+            resolve(body);
+          } else {
+            reject(body);
+          }
+        });
+      });
     }
 }
 
diff --git a/test/unit/webui/components/__mocks__/api.js b/test/unit/webui/components/__mocks__/api.js
index 2c8e2cf3e..afd8eeb44 100644
--- a/test/unit/webui/components/__mocks__/api.js
+++ b/test/unit/webui/components/__mocks__/api.js
@@ -22,11 +22,7 @@ const register = (url, method = 'get', options = {}) => {
 
   if (url === 'sidebar/verdaccio' && method.toLocaleLowerCase() === 'get') {
     return new Promise(function(resolve) {
-      resolve({
-        json: function() {
-          return packageMeta;
-        }
-      });
+      resolve(packageMeta);
     });
   }
 
diff --git a/test/unit/webui/components/header.spec.js b/test/unit/webui/components/header.spec.js
index 2bb42f3ae..a0718d5be 100644
--- a/test/unit/webui/components/header.spec.js
+++ b/test/unit/webui/components/header.spec.js
@@ -55,7 +55,7 @@ describe('<Header /> component shallow', () => {
 
   it('handleSubmit - should give error for blank username and password', () => {
     const HeaderWrapper = wrapper.find(Header).dive();
-    const handleSubmit = HeaderWrapper.instance().handleSubmit;
+    const {handleSubmit} = HeaderWrapper.instance();
     const error = {
       description: "Username or password can't be empty!",
       title: 'Unable to login',
@@ -67,11 +67,14 @@ describe('<Header /> component shallow', () => {
 
   it('handleSubmit - should login successfully', () => {
     const HeaderWrapper = wrapper.find(Header).dive();
-    const handleSubmit = HeaderWrapper.instance().handleSubmit;
-
+    const {handleSubmit} = HeaderWrapper.instance();
+    const event = {preventDefault: () => {}}
+    const spy = jest.spyOn(event, 'preventDefault');
+    
     HeaderWrapper.setState({ username: 'sam', password: '1234' });
 
-    handleSubmit().then(() => {
+    handleSubmit(event).then(() => {
+      expect(spy).toHaveBeenCalled();
       expect(storage.getItem('token')).toEqual('TEST_TOKEN');
       expect(storage.getItem('username')).toEqual('sam');
     });
@@ -79,30 +82,37 @@ describe('<Header /> component shallow', () => {
 
   it('handleSubmit - login should failed with 401', () => {
     const HeaderWrapper = wrapper.find(Header).dive();
-    const handleSubmit = HeaderWrapper.instance().handleSubmit;
+    const {handleSubmit} = HeaderWrapper.instance();
     const errorObject = {
       title: 'Unable to login',
       type: 'error',
-      description: 'Unauthorized'
+      description: 'bad username/password, access denied'
     };
+    const event = { preventDefault: () => { } }
+    const spy = jest.spyOn(event, 'preventDefault');
     HeaderWrapper.setState({ username: 'sam', password: '12345' });
 
-    handleSubmit().catch((error) => {
+    handleSubmit(event).then(() => {
+      expect(spy).toHaveBeenCalled();
       expect(HeaderWrapper.state('loginError')).toEqual(errorObject);
     });
   });
 
   it('handleSubmit - login should failed with when no data is sent', () => {
     const HeaderWrapper = wrapper.find(Header).dive();
-    const handleSubmit = HeaderWrapper.instance().handleSubmit;
+    const {handleSubmit} = HeaderWrapper.instance();
     const error = {
       title: 'Unable to login',
       type: 'error',
       description: "Username or password can't be empty!"
     };
+    const event = { preventDefault: () => { } }
+    const spy = jest.spyOn(event, 'preventDefault');
+
     HeaderWrapper.setState({});
 
-    handleSubmit().then(() => {
+    handleSubmit(event).then(() => {
+      expect(spy).toHaveBeenCalled();
       expect(HeaderWrapper.state('loginError')).toEqual(error);
     });
   });
diff --git a/test/unit/webui/components/store/login.js b/test/unit/webui/components/store/login.js
index 35f6897fc..bbe89e9e1 100644
--- a/test/unit/webui/components/store/login.js
+++ b/test/unit/webui/components/store/login.js
@@ -4,21 +4,17 @@
  * @returns {promise}
  */
 export default function(config) {
-  return new Promise(function(resolve, reject) {
+  return new Promise((resolve, reject) => {
     const body = JSON.parse(config.body);
     if (body.username === 'sam' && body.password === '1234') {
-      return new Promise(function(resolve) {
         resolve({
-          json: function() {
-            return {
-              username: 'sam',
-              token: 'TEST_TOKEN'
-            }
-          }
+          username: 'sam',
+          token: 'TEST_TOKEN'
         });
-      });
     } else {
-      throw Error('Unauthorized');
+      reject({
+          error: 'bad username/password, access denied'
+      });
     }
   });
 }
diff --git a/test/unit/webui/components/store/logo.js b/test/unit/webui/components/store/logo.js
index 74162df22..11c4e9a3b 100644
--- a/test/unit/webui/components/store/logo.js
+++ b/test/unit/webui/components/store/logo.js
@@ -1,10 +1,12 @@
 /**
- * Mock response for login api
+ * Mock response for logo api
  * @returns {promise}
  */
 export default function() {
   const response = {
-    url: 'http://xyz.com/image.jpg'
+    text(){
+      return 'http://xyz.com/image.jpg';
+    }
   };
   return Promise.resolve(response);
 }