How does Google treat soft 404 errors, and what measures can be taken to avoid them?

Soft 404 errors can definitely cause some SEO headaches if not handled properly. Here's how:

Essentially, a soft 404 happens when your server returns a 200 OK status code for a URL that doesn't actually exist or is invalid. It should be returning a proper 404 Not Found error instead.

While Google's crawlers can detect these soft 404s, their algorithms will keep attempting to crawl and index those non-existent pages. This wastes your crawl budget and can potentially lead to indexing issues down the line.

If the soft 404 problem persists over time, Google may eventually just drop those pages from their index entirely. That's a sure way to lose visibility and potentially trigger ranking penalties for what looks like low-quality or thin content.

To avoid those consequences, there are a few key things you'll want to do:

1) Check your server and CMS configs to ensure 404s are actually being returned properly for invalid URLs. Misconfigurations here are often the culprit.

2) Implement a user-friendly 404 page packed with relevant links/resources to recover users who hit those errors. Reducing bounces helps.

3) Use tools like GSC, Screaming Frog, etc to regularly audit for soft 404s so you can fix them fast before they become bigger issues.

4) Set up proper 301 redirects and URL mapping rules to handle pages that have moved or no longer exist gracefully.

5) Update your XML sitemaps and remove any URLs that result in soft 404s, so Google doesn't waste time on them.

6) Do periodic content audits to remove/consolidate any old, thin pages that may be triggering soft 404 scenarios.

The need is to catch and resolve soft 404s quickly through proper configurations, redirects, and maintenance. Leave them unchecked and Google will inevitably stop indexing that low-quality content over time.