Link Checker marking otherwise working URLs as invalid

Description

Issue:
Link Checker marking working URLs as invalid. Hence, the links the pages appear as broken.
AEM Link Checker is getting a 404 response 1 when attempting to connect to the specific URLs, which are otherwise working.

Details:
If you check these URLs in an online tool (e.g.: https://reqbin.com/) that can submit ‘HEAD’ requests, and if you get 404 response, the Link Checker (from AEM 6.5 onwards) is working as designed.

Till AEM 6.4 release, the link checker would make both a HEAD and GET request when validating links.
This behavior was changed in AEM 6.5 to address a critical security vulnerability (CQ-4259662 | SSRF in the Linkchecker).
Hence, from AEM 6.5 onwards, the Link Checker will only submit HEAD requests.

1: 20.05.2020 17:53:07.783 *INFO* sling-default-2-com.day.cq.rewriter.linkchecker.impl.LinkCheckerTask.299567 com.day.cq.rewriter.linkchecker.impl.LinkCheckerTask Checked URL https://abc.xyz.com/def-efg: 404 (invalid)

Resolution

If the user is sure they still want the URLs to be marked as valid, and the links on the pages to work, they can follow below steps:

  • Go to /system/console/configMgr
  • Search for the config: “Day CQ Link Checker Service” and edit. Sharing a screenshot below
  • Add a regular expression value to the “Link Check Override Patterns”. The URLs that match this pattern shall not be checked by the link checker, (but must be a valid uri anyways).
  • Example: https://abc.xyz.com/
  • One can also follow this knowledge article for more options: https://helpx.adobe.com/experience-manager/kb/DisableLinkChecker.html

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