What Does "Mixed Redirects" Mean?
A mixed redirect is when there are 2 or more other URLs redirects strung together in a chain, but the HTTP Status is not the same for all redirects. Typically, this involves both 301 redirects and 302 redirects being used in the same chain.
What’s the difference between a 301 and a 302 redirect?
There are a number of HTTP status codes that could be classified as redirects, but we're generally most concerned with two: 301 and 302. Generally speaking, 301s are usually best for SEO, but 302s also serve a purpose:
301 Permanent Redirect – This type of redirect is used to signal that the redirect is permanent - the old URL will not be used again. This is generally the type of redirect you want to use on your site. That's because 301 permanent redirects typically pass all the link juice from the first URL to the target URL. Therefore, when a page moves, it's possible to keep the same ranking position with the new URL, thus preserving your SEO efforts. It's also a signal to search engines that the original URL is no longer used, so they will generally remove it from their index.
302 “Temporary Redirect” – In contrast to a 301 redirect, a 302 redirect is interpreted by search engines that the redirect is a temporary phenomenon and could change back at any time. Because of this, search engines may not remove the original URL from their index and may not pass any link juice to the target URL since they expect this situation to be temporary. This means that if a high-ranking URL moves to a new domain or a new location somewhere else on your site, all of the hard work you've put into getting the first URL ranking well will not be passed on to the new URL location. This can be disastrous for your site's rankings, and therefore is not advised in most situations.
Why It's Important
Both a 301 and 302 redirect are used for different purposes, and each sends a different message to search engines. If they are both used in the same chain, search engines will not know how to treat the URLs. For example,
Is it actually a temporary redirect or a permanent one?
Should search engines remove the URL from the index or leave it?
Should search engines pass link juice to the target URL or not?
Therefore, it’s not possible to predict how search engines will treat these URLs, and unintended consequences could result.
How to Fix
The best way to fix this issue is to do remove the redirect chain completely. Redirect the URL to the final destination URL in the redirect chain, thus cutting out intermediate steps. Then go to all other steps in the chain and do the same.
If this is not easily possible, change the status of all the redirects in the chain to the same status. If these redirects should be permanent, use a 301 for all redirects in the chain. If it’s only temporary, consider using 302 redirects.