Hello,
I can read here and then some people advising to netinstall the device with RouterOS 7, if it comes from RouterOS 6.
Instead of simply updating the packages from RouterOS 6 to RouterOS 7.
Why ?
Is this recommendation documented somewhere ?
Does it come from MikroTik support ?
Thank you !
There are still some bugs hanging around w.r.t. to config settings not transferring nicely from ROS6 to ROS7 (even if you already had some intermediate ROS7 versions).
This is config related.
And there is also a problem with parts of config simply disappearing. That’s filesystem.
That’s confirmed by some users (luckily very rare !) but it’s not clear yet what causes it from happening.
Safest approach in such cases is indeed clean install (upgrade and perform reset with default config), or you can also use netinstall.
But it does not provide a solution for all those devices in the field which need to be upgraded sooner or later.
This needs to be fixed, that’s clear.
I also had to clean install one time already a Hex device because of such issues (I think, couldn’t find any other explanation since applied config before and after was EXACT the same yet it worked afterwards).
Not a problem for me, that Hex is a home router and I love to thinker / experiment / … but I can imagine the nightmare for people experiencing such issues in real productive environments with clients involved …
Thank you @holvoetn for explanation 
One additional question, let’s assume I have a device, installed with RouterOS 6.
Will the following procedure…
… produce the same final result as a netinstall ?
Or does perhaps RouterOS 7 comes with a specific new underlying filesystem / filesystem arrangement (or whatever else) only netinstall will properly set ?
Thank you again !
If you really REALLY want to start as clean as possible, netinstall is the way.
But it can sometimes require multiple attempts to succeed.
There is no need to move to version 7 from the latest versions of 6. for example 6.48.6 or 6.49.5
Depends if you want to use new features or not. You can not have wireguard on ROS6, no container support either (it’s not in ROS7 anymore either 
), no IPV6 NAT, …
And that was not the question.
Adding:
when moving from ROS6 to ROS7 there is always a possibility something is left which might causes problems later on.
It shouldn’t but it can happen.
When using netinstall this is impossible. You start clean from that version and nothing else.
I think this is really for devices with issues like when they are in bootloops or are unable to boot up at all, with a normal netinstall it should be pretty easy as long as you set everything up correctly.
I recommend connecting the device directly to the PC as you dont have to worry about anything else preventing the packets to/from the netinstall server and device as well as you can watch the ethernet interface.
Before I even open up netinstall I will check if the firewall as well as any virtual adapters like the virtual switches hyperV can install are disabled then while holding down the reset button I watch to see the ethernet ports behaviour on the network status tab, from what I have experienced you should get an initial layer 1 connection then it will drop for a bit then come back up, once it comes back up shortly after it should show up in netinstall.
As well as this there is a bit of a bug with netinstall, if it shows up in the windows and you click the install button but it goes back to ready all you need to do is close off the netinstall program without restarting the whole netinstall procedure again and the device should show up right away and should be able to be netinstalled correctly