Starting today, Google has made troubleshooting hreflang annotations easier. Now, it will help you to identify 2 of the most common issues associated with hreflang annotations.You can find these errors located in the International Targeting section under Search Traffic. The issues are given below:
Missing Return Links
If the pages in your site has missing return hreflang annotations links then Google will find such links and display them in GWT.
Incorrect hreflang Values
The value of the hreflang should be a language code in ISO 639-1 format such as “es”, or a combination of language and country code such as “es-AR”. If the URL’s are not in the proper format then Google will provide example URLs to help you fix them.
Also, Google has moved the geographic targeting setting under the International Targeting section, for easier management of multilingual sites.
Also See:
Solving Duplicate Content Issue of Multi Language Sites
Search Queries in Webmasters Tool
How to Find Out the Total Number of Pages Blocked by Robots.txt
Google Tag Manager
Google Adwords Bidding
Multi Channel Funnel in Google Analytics
Duplicate Content and SEO
HTTP and HTTPS in SEO