I have upgraded RB230 from V. 2.8.26 to 2.9 with routeros-x86-2.9.npk. After rebooting RB have system package only. What's wrong?
With another router on PC I have no problem with upgrading from V. 2.9.rc6.
Now I have telnet access only to broken RB and can't do anymore.
Tomorrow I'll try to upload additional packages.
Or may be best way is to downgrade?
The routeros-x86-2.9 package can be only used to upgrade from v2.9RC's. If you have older version, such as v2.8.x then you should use regular packages. When you will have v2.9 then in future for upgrade to the newest version you will be able to use this big package.
In your case - install the additional packages that you are missing now after upgrade.