I'm trying to clean up my main site to remove as many barriers to natural SERP as possible and have been monitoring Google Webmaster Tools closely - especially crawl errors.
One error that i've seen recently is the HTML error witrh code 400 which google define as:
400 (Bad request) The server didn't understand the syntax of the request.
I've been fixing other crawl errors, 'not followed' and 'not found' errors with .htaccess and robot.txt edits but I dont know much about 400 errors.
From what i've read its where the user types in the wrong address or uses an unsupported browser? Is that right?