When I try to upgrade my RouterOS x86:
Current Version 6.25
Latest Version 6.31
I get a loop of “ERROR: missing isdn-6.31.npk” - any ideas?
I resolved this by removing the isdn package manually from the RouterOS.
Always nervous whenever I upgrade these images - this time is no exception. I’ve told it to download/upgrade twice (did reboot), but came back with the original version still. Manual reboot as well - same thing. Now reports as:
Current Version 6.25
Latest Version (blank)
Not sure if you’re aware, but the most stable RouterOS seems to be the bugfix versions of 6.30.x which is currently on 6.30.4.
No new features introduced into the bugfix version, just resolving bugs as the name suggests 
Details here:
http://www.stubarea51.net/2015/08/04/mikrotik-unveils-new-routeros-development-cycle/
Thanks for that - how do I downgrade to that version, given that my RouterOS is showing 6.31 as the only option?
I had 6.30.2 installed , then upgrade it from winbox, to last stable 6.31. when my RB750 reboot, it continuously blink for link connection on/off/on/off (Routerboard firmware 3.24)
Router is not answer for any packets. Reset for default settings not helped. It continues blink. I was able to downgrade it to 6.30.4 but this not helped. then I downgrade it to 6.30.2 and restore configuration. It helped. Then I try with second RB750 (some different configuration with CAPsMAN) and it was the same. My RBmAP2n normally upgrade to 6.31 and work with 6.30.2 CAPsMAN server
Maybe I did something wrong but I can’t start with netinstall, It did not appear in Netinstall list =(
You can download it from http://www.mikrotik.com/download and select “Bugfix (6.30.4)” or click on the link:
http://download2.mikrotik.com/routeros/6.30.4/all_packages-x86-6.30.4.zip
Extract the files and in winbox open the “Files” and drag ‘n’ drop any package you are using.
The packages those are installed to your router you can find them in System->Packages.
In there click the “downgrade” and follow the prompt. After the router reboots, you will have the 6.30.4 version installed.
Hmm.. and if I don’t have Windoze? (OSX)
Can you upload them via webfig?
There should be a dropdown and you can actually select an “upgrade” to 6.30.4 bugfix.