Skip to content
    Moz logo Menu open Menu close
    • Products
      • Moz Pro
      • Moz Pro Home
      • Moz Local
      • Moz Local Home
      • STAT
      • Moz API
      • Moz API Home
      • Compare SEO Products
      • Moz Data
    • Free SEO Tools
      • Domain Analysis
      • Keyword Explorer
      • Link Explorer
      • Competitive Research
      • MozBar
      • More Free SEO Tools
    • Learn SEO
      • Beginner's Guide to SEO
      • SEO Learning Center
      • Moz Academy
      • MozCon
      • Webinars, Whitepapers, & Guides
    • Blog
    • Why Moz
      • Digital Marketers
      • Agency Solutions
      • Enterprise Solutions
      • Small Business Solutions
      • The Moz Story
      • New Releases
    • Log in
    • Log out
    • Products
      • Moz Pro

        Your all-in-one suite of SEO essentials.

      • Moz Local

        Raise your local SEO visibility with complete local SEO management.

      • STAT

        SERP tracking and analytics for enterprise SEO experts.

      • Moz API

        Power your SEO with our index of over 44 trillion links.

      • Compare SEO Products

        See which Moz SEO solution best meets your business needs.

      • Moz Data

        Power your SEO strategy & AI models with custom data solutions.

      Enhance Keyword Discovery with Bulk Analysis
      Moz Pro

      Enhance Keyword Discovery with Bulk Analysis

      Learn more
    • Free SEO Tools
      • Domain Analysis

        Get top competitive SEO metrics like DA, top pages and more.

      • Keyword Explorer

        Find traffic-driving keywords with our 1.25 billion+ keyword index.

      • Link Explorer

        Explore over 40 trillion links for powerful backlink data.

      • Competitive Research

        Uncover valuable insights on your organic search competitors.

      • MozBar

        See top SEO metrics for free as you browse the web.

      • More Free SEO Tools

        Explore all the free SEO tools Moz has to offer.

      NEW Keyword Suggestions by Topic
      Moz Pro

      NEW Keyword Suggestions by Topic

      Learn more
    • Learn SEO
      • Beginner's Guide to SEO

        The #1 most popular introduction to SEO, trusted by millions.

      • SEO Learning Center

        Broaden your knowledge with SEO resources for all skill levels.

      • On-Demand Webinars

        Learn modern SEO best practices from industry experts.

      • How-To Guides

        Step-by-step guides to search success from the authority on SEO.

      • Moz Academy

        Upskill and get certified with on-demand courses & certifications.

      • MozCon

        Save on Early Bird tickets and join us in London or New York City

      Access 20 years of data with flexible pricing
      Moz API

      Access 20 years of data with flexible pricing

      Find your plan
    • Blog
    • Why Moz
      • Digital Marketers

        Simplify SEO tasks to save time and grow your traffic.

      • Small Business Solutions

        Uncover insights to make smarter marketing decisions in less time.

      • Agency Solutions

        Earn & keep valuable clients with unparalleled data & insights.

      • Enterprise Solutions

        Gain a competitive edge in the ever-changing world of search.

      • The Moz Story

        Moz was the first & remains the most trusted SEO company.

      • New Releases

        Get the scoop on the latest and greatest from Moz.

      Surface actionable competitive intel
      New Feature

      Surface actionable competitive intel

      Learn More
    • Log in
      • Moz Pro
      • Moz Local
      • Moz Local Dashboard
      • Moz API
      • Moz API Dashboard
      • Moz Academy
    • Avatar
      • Moz Home
      • Notifications
      • Account & Billing
      • Manage Users
      • Community Profile
      • My Q&A
      • My Videos
      • Log Out

    The Moz Q&A Forum

    • Forum
    • Questions
    • Users
    • Ask the Community

    Welcome to the Q&A Forum

    Browse the forum for helpful insights and fresh discussions about all things SEO.

    1. Home
    2. SEO Tactics
    3. Technical SEO
    4. Robots.txt and canonical tag

    Moz Q&A is closed.

    After more than 13 years, and tens of thousands of questions, Moz Q&A closed on 12th December 2024. Whilst we’re not completely removing the content - many posts will still be possible to view - we have locked both new posts and new replies. More details here.

    Robots.txt and canonical tag

    Technical SEO
    3
    7
    3537
    Loading More Posts
    • Oldest to Newest
    • Newest to Oldest
    • Most Votes
    Reply
    • Reply as question
    Log in to reply
    This topic has been deleted. Only users with question management privileges can see it.
    • seoug_2005
      seoug_2005 last edited by

      In the SEOmoz post - http://www.seomoz.org/blog/robot-access-indexation-restriction-techniques-avoiding-conflicts, it's being said -

      If you have a robots.txt disallow in place for a page, the canonical tag will never be seen.

      Does it so happen that if a page is disallowed by robots.txt, spiders DO NOT read the html code ?

      1 Reply Last reply Reply Quote 0
      • seoug_2005
        seoug_2005 @seoug_2005 last edited by

        Thanks Ryan for explaining things very clearly.

        1 Reply Last reply Reply Quote 0
        • RyanKent
          RyanKent @seoug_2005 last edited by

          What we know is there have been many cases where a page that is blocked in robots.txt has appeared in search results. The explanation provided is that robots.txt blocks crawlers during normal site visits, but not necessarily on visits where they are following links from other sites.

          1 Reply Last reply Reply Quote 1
          • seoug_2005
            seoug_2005 @RyanKent last edited by

            If spiders follow links to an article on my site, will they read the contents then ?  If the canonical tag is on article page itself, will canonical  tag will be seen ?

            RyanKent seoug_2005 2 Replies Last reply Reply Quote 0
            • RyanKent
              RyanKent last edited by

              Daylan offered a great answer but I would like to add one exception. When crawlers from the major SEs visit your site they will honor your robots.txt file but sometimes they will follow links from other sites to an article on your site, and during that particular visit they will not see the robots.txt file and index your page.

              This is one of the reasons why your robots.txt file should be used as minimally as possible, and when it is used you should have a backup process in place such as the canonical or noindex tag on a page.

              seoug_2005 1 Reply Last reply Reply Quote 1
              • seoug_2005
                seoug_2005 @Daylan last edited by

                Thanks Daylan for your quick response. I just wanted a second opinion that canonical tag will never be seen if a page is disallowed.

                1 Reply Last reply Reply Quote 0
                • Daylan
                  Daylan last edited by

                  Thats correct in most cases:

                  It works likes this: a robot wants to vists a Web site URL, say http://www.example.com/welcome.html. Before it does so, it firsts checks for http://www.example.com/robots.txt, and finds:

                  User-agent: *
                  Disallow: /

                  The "User-agent: *" means this section applies to all robots. The "Disallow: /" tells the robot that it should not visit any pages on the site.

                  Robots can ignore your /robots.txt. Especially malware robots that scan the web for security vulnerabilities, and email address harvesters used by spammers will pay no attention.

                  More information available here about:

                  http://www.robotstxt.org/

                  seoug_2005 1 Reply Last reply Reply Quote 1
                  • 1 / 1
                  • First post
                    Last post

                  Got a burning SEO question?

                  Subscribe to Moz Pro to gain full access to Q&A, answer questions, and ask your own.


                  Start my free trial


                  Browse Questions

                  Explore more categories

                  • Moz Tools

                    Chat with the community about the Moz tools.

                  • SEO Tactics

                    Discuss the SEO process with fellow marketers

                  • Community

                    Discuss industry events, jobs, and news!

                  • Digital Marketing

                    Chat about tactics outside of SEO

                  • Research & Trends

                    Dive into research and trends in the search industry.

                  • Support

                    Connect on product support and feature requests.

                  • See all categories

                  Related Questions

                  • CREW-MARKETING

                    Quick Fix to "Duplicate page without canonical tag"?

                    When we pull up Google Search Console, in the Index Coverage section, under the category of Excluded, there is a sub-category called ‘Duplicate page without canonical tag’.  The majority of the 665 pages in that section are from a test environment. If we were to include in the robots.txt file, a wildcard to cover every URL that started with the particular root URL ("www.domain.com/host/"), could we eliminate the majority of these errors? That solution is not one of the 5 or 6 recommended solutions that the Google Search Console Help section text suggests.  It seems like a simple effective solution.  Are we missing something?

                    Technical SEO | | CREW-MARKETING
                    1
                  • bill369

                    Do Canonical Tags Pass Link Juice?

                    I have an ecommerce website where some pages link to a product page with a different URL. EXAMPLE: 1: /category/product1.html (not indexed by Google) with canonical pointing to product1.html Other page link to the product like below. 2: product1.html (indexed by Google) Now the question is, does 1: pass any link juice to product1.html or not? Is it worth to change everything and link only to one URL? My site is running on Magento!

                    Technical SEO | | bill369
                    0
                  • SoulSurfer8

                    How long does it take for canonical tags to work

                    How long on average does it take for a canonical tag to work? Understand that canonicals are just a suggestion, but after adding a canonical tag and submitting the page via Google fetch, assuming Google follows the canonical, would you expect it to work after a day or two or does it take longer? We added canonicals to old PPC landing pages that are ranking organically, though our new landing pages (which we want to rank organically) are not identical and have a bit more content/features. They are similar though. Canonicals were added to the old pages (pointing to new pages) and requested indexing via search console. Old pages are still ranking and new pages not so much. FYI we are unable to 301 old PPC pages due to other non negotiable reasons unfortunately. Thanks.

                    Technical SEO | | SoulSurfer8
                    0
                  • Webicultors

                    Is sitemap required on my robots.txt?

                    Hi, I know that linking your sitemap from your robots.txt file is a good practice. Ok, but... may I just send my sitemap to search console and forget about adding ti to my robots.txt? That's my situation: 1 multilang platform which means... ... 2 set of pages. One for each lang, of course But my CMS (magento) only allows me to have 1 robots.txt file So, again: may I have a robots.txt file woth no sitemap AND not suffering any potential SEO loss? Thanks in advance, Juan Vicente Mañanas Abad

                    Technical SEO | | Webicultors
                    0
                  • kcb8178

                    Is there a limit to how many URLs you can put in a robots.txt file?

                    We have a site that has way too many urls caused by our crawlable faceted navigation.  We are trying to purge 90% of our urls from the indexes.  We put no index tags on the url combinations that we do no want indexed anymore, but it is taking google way too long to find the no index tags.  Meanwhile we are getting hit with excessive url warnings and have been it by Panda. Would it help speed the process of purging urls if we added the urls to the robots.txt file?  Could this cause any issues for us?  Could it have the opposite effect and block the crawler from finding the urls, but not purge them from the index? The list could be in excess of 100MM urls.

                    Technical SEO | | kcb8178
                    0
                  • joshcanhelp

                    Invisible robots.txt?

                    So here's a weird one... Client comes to me for some simple changes, turns out there are some major issues with the site, one of which is that none of the correct content pages are showing up in Google, just ancillary (outdated) ones. Looks like an issue because even the main homepage isn't showing up with a "site:domain.com" So, I add to Webmaster Tools and, after an hour or so, I get the red bar of doom, "robots.txt is blocking important pages." I check it out in Webmasters and, sure enough, it's a "User agent: * Disallow /" ACK! But wait... there's no robots.txt to be found on the server. I can go to domain.com/robots.txt and see it but nothing via FTP. I upload a new one and, thankfully, that is now showing but I've never seen that before. Question is: can a robots.txt file be stored in a way that can't be seen? Thanks!

                    Technical SEO | | joshcanhelp
                    0
                  • Leighm

                    Should there be a canonical tag on my 404 error page?

                    In my crawl diagnostics, I notice some 4xx client errors. They are appearing for pages that no longer exist, so I'm not sure what the problem is. Shouldn't they just be dealt as 404's? Anyway, on closer inspection I noticed that my 404 error page contains a canonical tag which points to the missing page. Could this be the issue? Is it a good idea to remove the canonical tag from this error page? Thanks.

                    Technical SEO | | Leighm
                    0
                  • JordanJudson

                    Should I set up a disallow in the robots.txt for catalog search results?

                    When the crawl diagnostics came back for my site its showing around 3,000 pages of duplicate content. Almost all of them are of the catalog search results page. I also did a site search on Google and they have most of the results pages in their index too. I think I should just disallow the bots in the /catalogsearch/ sub folder, but I'm not sure if this will have any negative effect?

                    Technical SEO | | JordanJudson
                    0

                  Get started with Moz Pro!

                  Unlock the power of advanced SEO tools and data-driven insights.

                  Start my free trial
                  Products
                  • Moz Pro
                  • Moz Local
                  • Moz API
                  • Moz Data
                  • STAT
                  • Product Updates
                  Moz Solutions
                  • SMB Solutions
                  • Agency Solutions
                  • Enterprise Solutions
                  • Digital Marketers
                  Free SEO Tools
                  • Domain Authority Checker
                  • Link Explorer
                  • Keyword Explorer
                  • Competitive Research
                  • Brand Authority Checker
                  • Local Citation Checker
                  • MozBar Extension
                  • MozCast
                  Resources
                  • Blog
                  • SEO Learning Center
                  • Help Hub
                  • Beginner's Guide to SEO
                  • How-to Guides
                  • Moz Academy
                  • API Docs
                  About Moz
                  • About
                  • Team
                  • Careers
                  • Contact
                  Why Moz
                  • Case Studies
                  • Testimonials
                  Get Involved
                  • Become an Affiliate
                  • MozCon
                  • Webinars
                  • Practical Marketer Series
                  • MozPod
                  Connect with us

                  Contact the Help team

                  Join our newsletter
                  Moz logo
                  © 2021 - 2025 SEOMoz, Inc., a Ziff Davis company. All rights reserved. Moz is a registered trademark of SEOMoz, Inc.
                  • Accessibility
                  • Terms of Use
                  • Privacy

                  Looks like your connection to Moz was lost, please wait while we try to reconnect.