From several machines, when opening Winbox to a 2.9.38 machine, Winbox opens and then closes right away. Any idea why this might be happening?
My 532 board at home mysteriously stopped working with Winbox a few days ago. No configuration changes were made to the router in question, and Winbox works fine with the other 532 boards. I did an upgrade, reloaded Winbox on my PC, and I’m still having the same issue. Telnet and SSH work to the board in question, and the log shows my login attempts via winbox as OK.
When I access the router via winbox using either the IP or MAC on any interface, winbox opens and immediately closes with no error message.
Very strange, especially since it works fine with the other boards…
Whenever this happens to me, I give the IP address instead of the MAC Address. As IP corrects errors, it ensures connection keeps working.
Do try it! 
Try to loging through IP address instead of MAC. It will Work.
Ashish.
I have tried it by IP, on every interface. I just tried it from a different PC, same results…
I found the issue on my router that was having the same issue. Uncheck “Load Previous Session” in the Winbox login window before hitting the connect button.
I’m not sure why this worked, but it did. The best theory I can come up with is that the router was holding onto a corrupt Winbox session, which was persisting in memory after reboot. Once I cleared the issue, I was able to log in with “Load Previous Session” checked without any issues.
This happens somtimes here too. I don’t care for the previous session option anyway. I just wish that WinBox loader would remember the uncheck.
I was facing same problem one of my MikroTiK device. After upgrading the OS problem has been solved.
Hi All
If you are facing winbox suddenly close as soon as open then follow below
before click on connect, Click on tools > then click on Move Session Folder > Delete session folder and try to login
it should work fine
