Summary

Some Jira users are unable to upload or open an attachment from a Jira issue in Chrome due to the error ERR_BLOCKED_BY_CLIENT. Note that these users might get the same error while performing other actions in Jira, so the error is not only limited to attachments.

Environment

Jira Server / Data Center, any version from 8.0.0

Diagnosis

• When uploading or downloading an attachment (or performing some other actions) while using Chrome, the following error is thrown in the browser:

  <Some_Jira_URL> is blocked
  This page has been blocked by Chrome
  ERR_BLOCKED_BY_CLIENT

  
  

• The error does not occur in other browsers or when using Chrome in incognito mode
• The same ERR_BLOCKED_BY_CLIENT error will be observed in the HAR file and/or Console file generated by the browser while replicating the issue

Cause

There is a browser extension installed in Chrome which blocks the URL that Jira needs to load. Some examples of add-ons which are known to cause this issue are listed below:

• Adblock (or any other Browser Safety extension), as explained in the article How to Solve ERR_BLOCKED_BY_CLIENT
• The extension Office Editing for Docs, Sheets & Slides is known to prevent Jira users from downloading attachments

Solution

The solution will depend on the extension that is causing the error:

• If the error is coming from a browser safety extension such as Adblock:
  • Disable the extension. This is the simplest solution. If you choose to want to see the resources which are being blocked, simply disable the Adblock extension which is generating the error.
  • Whitelist the domain. In many extensions that produce this error, you as a user can also whitelist particular domains. Therefore if you trust a domain and don't want to block any resources, this will also resolve the ERR_BLOCKED_BY_CLIENT error.
• If the error is coming from other extensions such as Office Editing for Docs, Sheets & Slides:
  • your only option might be to disable the extension, unless this extension has some whitelisting configuration