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Synchronous XHR in page dismissal - Errors in KTA after update to Chrome 80

Chrome has deprecated functionality referred to as “synchronous XHR requests during page dismissal,“ which requires updating KTA to a compatible version.
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Question / Problem: 

Why would errors start to occur in KTA after updating to Chrome version 80?

Answer / Solution: 

Chrome has deprecated functionality referred to as “synchronous XHR requests during page dismissal.“  Kofax TotalAgility previously used this functionality, but has removed in the latest versions.  Using Chrome version 80 or newer with older versions of KTA will result in two issues.

Unable to Scan

After updating to Chrome version 80, affected versions of KTA are not able to gracefully shut down the Web Capture Service process used for scanning.  So a scan user would experience the following:

  1. Open a scan form for the first time, and scan the first batch of images.
  2. Create the job successfully.
  3. In the browser dev console there will be an error about using synchronous XHR.
  4. Unable to scan a second batch of images.

 

Release notes refer to this issue as “Web Capture Service JS API use deprecated feature to send web requests synchronously.”  It is resolved in the following versions as well as any subsequent versions:

  • 7.2.2.13
  • 7.3.2.18
  • 7.4.1.18
  • 7.5.0.11
  • 7.6.0.0

Error When Navigating Away From Activity

SyncXHRfailure.png

After updating to Chrome version 80, affected versions of KTA may produce an error and leave the activity locked if navigating to another page without clicking cancel.  One possible error message is "Failed to execute 'send' on 'XMLHttpRequest': Failed to load 'http://servername/TotalAgility/Servi...vc/json/Unload' Synchronous XHR in page dismissal."

This happens as KTA tries to use a synchronous XHR request to cancel the activity and unlock the folder.  This does not apply to KTA 7.2, because it does not try to cancel the activity or unlock the folder.  In KTA 7.3, the cancel/unlock attempt only occurs when Redirect Confirmation is enabled on the form.  In all later versions the cancel/unlock attempt always occurs.  This issue is not explicitly listed in release notes, but is resolved in the following versions as well as any subsequent versions:

  • 7.3.2.18
  • 7.4.1.19
  • 7.5.0.13
  • 7.6.0.1
  • 7.7.0.0

Temporary Workaround

In environments where enterprise policies are used to manage Chrome settings, a policy can be set to temporarily opt out of this change and continue to use the deprecated functionality.  This policy is expected to be removed in Chrome version 82, however this can provide more time to update to a compatible version of KTA.

https://cloud.google.com/docs/chrome-enterprise/policies/?policy=AllowSyncXHRInPageDismissal

Further Details

For more details and discussion on this specific change in Chrome:
https://www.chromestatus.com/feature/4664843055398912

For expected release date of Chrome versions:
https://chromiumdash.appspot.com/schedule