There are a lot of times when an SEO crawler finds a fatal error where you need to be sure you take care of it as soon as possible. You might think that everything bad that a crawler finds are automatically bad and they might spell bad news for your website, but there are times when those errors aren’t errors at.
Even the most popular crawling tools can find issues that aren’t really issues. So when your crawler of choice does find an issue, is it possible to tell the difference to avoid prioritizing a fix that doesn’t really need to be worked on at all?
If you want to see some actual examples, then Olga Zarzeczna has a column on Search Engine Journal so you can check out the explanations as to why they may be an issue for your site or not.