If you are here on this page to fix Google AdSense crawl errors then that means you've got your AdSense account approved. So first of all "Congrats!"
The reason I wished "Congrats" is because getting Google AdSense Approval is not an easy task these days no matter how much efforts you put into starting a blog. Google has tightened their policies because of an increasing number of policies violations.
In case you are still struggling with your AdSense account approval then check this guide: 10+ Powerful Tricks To Get AdSense Approval Fast
Fix Google AdSense Crawl Errors For WordPress
Ok, finally you have an AdSense account. On the first day of approval, you felt pleased. But the problem is that as soon as AdSense starts crawling your site, it shows some crawl errors which affect your "Revenue Optimization" value.
To boost your AdSense income, feel free to check this guide: 11 Revenue Optimization Tricks To Boost Google AdSense Income
To fix this issue, I’m using Robots.txt file method. Just because it is the easiest way to prevent web crawlers and other web robots from accessing all or some part of a website which are otherwise publicly viewable. So we'll restrict some significant portions of our site like wp-admin, index.php, preview pages etc.
For this, add the following given lines to your WordPress site's Robots.txt file:
This method will surely solve your problem as it did for me. Now, wait for at least 24 hours until Google recrawls your site. If you have any doubts or queries regarding this tutorial, then feel free to ask in the comments section below.