When I link 2 tickets using blocked by it prevented the ticket that is blocked by from being closed.

[Dominic Hurst]

We are using 7.13 and using the blocked by no longer prevents you from closing the ticket that is "blocked by" another ticket. I am 100% sure that we had this working before but from my research this is only possible via plugin's is this true?

[Jakob KN]

Hi Dominic, 

The names of the issue links only show the relationship between issues, and provide useful info to the user. It will not actively block an issue from being resolved.

To my knowledge this have not been the case in previous versions of Jira either.

You could possibly add a Validator on your workflow transition, which would block the transition based on the linked issues status/resolution.

You can see more about advanced workflow configuration here:
https://confluence.atlassian.com/adminjiracloud/advanced-workflow-configuration-776636620.html#Advancedworkflowconfiguration-validators

[Dominic Hurst]

will check it out, thanks

[Jakob KN]

You're welcome.

If this solves your issue, feel free to accept my answer.
This makes it easier for other users to find a solution if they have the same question.