Crawled - currently not indexed
Reasons:
Noindex Meta Tag: The page may contain a meta tag in its HTML code with the directive <meta name="robots" content="noindex">. This tag instructs search engines not to index the page.
Robots.txt File: The website's robots.txt file may be blocking search engine bots from indexing certain pages or sections of the site.
Canonicalization Issues: If there are multiple versions of the same content (for example, both www and non-www versions of a page), and canonicalization is not properly implemented, search engines may choose not to index one of the versions.
Redirects: If the page redirects to another URL (especially with a 302 temporary redirect), search engines may not index the page at the redirected location.
Server Issues: If the server hosting the website is experiencing problems or is misconfigured, search engines may have difficulty accessing and indexing the content.
Content Quality: Search engines aim to provide users with high-quality and relevant content. If the content on the page is thin, duplicate, or of low quality, search engines may choose not to index it.
Crawl Budget: Search engines allocate a certain amount of resources (crawl budget) to each website. If a site has a large number of pages or if the pages are not frequently updated, search engines may not index all pages during a single crawl.
Penalties: If a website violates search engine guidelines, it may receive penalties, leading to some or all of its pages not being indexed.
New or Low-Priority Content: Search engines may prioritize indexing pages that are more relevant, authoritative, or popular. New or less important pages may not be indexed immediately.
Duplicate, Google chose different canonical than user
Reason:
This error means that Google thinks that the tested page isn't a duplicate of the user-declared canonical. Instead, Google thinks that the tested page is a duplicate of the Google-selected canonical.
If the Google-selected canonical is the tested page, then Google thinks that the tested page isn't similar to any other pages.
If the user-declared canonical is not similar to the current page, then Google won't ever choose that URL as canonical. A duplicate page must be similar to the canonical. (That's what duplicate means.)
Discovered – currently not indexed
Reason:
content quality
internal linking - Internal links are links from one page on your website to another. Google often sees URLs without any or many internal links as unimportant and may not index them. You can check if a URL has internal links for free with AWT.
crawl budget - Crawl budget is how fast and how many pages a search engine wants to crawl on your site. If your crawlable URLs exceed your crawl budget, you may see the “Discovered - currently not indexed” warning.
Page with redirect
Reason:
It means that some of your pages aren’t indexed because users and crawlers entering them are redirected to other URLs. Google will index the target URL instead.
In most cases, having redirected pages is normal and poses no danger to the visibility of your website.