Hi Gökhan,

I am sorry for the delay of this reply. After a while troubleshoot this issue, I've inspected the reason why you cannot run the cron using the link is because, there quite a few subscriber input wrong or not proper email address. I've delete the email that caused issue and it working perfectly fine now.
Besides, I'm not sure what version you're using currently, but surely this is the older version, can you please update to the latest version, so that you will not encounter this kind of issue again ?

The problem was again.

Hey there,

I've help you removed those invalid email notification from your backend.

And I also noticed your post subscriber email address is invalid, you can check my screenshot below.

To fix this, you have to go to backend > Easydiscuss > subscription > filter to post subscription > delete all the invalid email address user, so that when the post their subscribed before, the system will not generated their email to these invalid email address user.