Hello
I have error messages in logfile after update every time i log in with winbox or making any setting adjustment:

could not save configuration changes, not enough storage space available

I already have similar problem with previous version of this router, the internal flash size was too small and i cant download and install any update.
so i replaced it with newer model.
I believed mikrotik make better hardware with new version. or they are still on the same level ? what do you think ? how it is possible to free up some space on flash ?

Your device only has 16mb storage.
And starting ROS7.13 or about, that became a real problem for such devices.

Netinstall is the only way out, I'm afraid.

If you delete the backup file, you'd have 36K, which might be enough to save the config. And beta versions are often initially bigger than final versions - making them very tricky on the 16MB flash units. But netinstall is about only way to free up more space.

Of note here, this is an LMT-branded Chateau (MT has some deal with Latvia cell provider)... so there is a "branding kit" also installed...which is also "hidden" and using a small amount of space. So if you do "netinstall", you can decide if you want to remove the branding kit too (which may free small amount of space, but defaults will then be MikroTik's normal, not LMT — which should not matter if you're restoring a backup).

Others have mostly said the important things. Sadly, the 16MB flash has proven to be quite restrictive and as newer and newer features are added to RouterOS in every version its becoming increasingly tight.

General advice:
* avoid anything that may consume large amounts of storage: logs stored on disk, graphs stored on disk, large number of certificates, large address lists (thousands of addresses/prefixes, small ones are totally fine)
* basically the sure way to free up space is to netinstall the device
* a backup or export of your current configuration *can* be created even if no space is available on the device, but you manually have to specify the output file of the operation as being in the root of the filesystem (this is a ramdrive, so of course download it before rebooting)
* in my experience updating RouterOS leaves behind a varying amount of old configuration (which is logical - in case the naming, etc. of something was changed and you later choose to downgrade, it would be unfortunate to have the old config erased), and as a result of this I usually upgrade 16MB devices more rarely than others and do a full netinstall to the new version
* beta versions are quite often larger than the properly released ones - some hand optimization is probably done when promoting a beta to a stable version

Also, I'm not sure what specific things are included LMT branded ones.... But it MIGHT include TR-069 package, which also use some "disk" space.
To check see if tr069 is shown under System > Package. If so, you can uninstall that package (and can always add it back to enable LMT control of your router later).

See viewtopic.php?p=1136075

Already removed the package and opened port instance in firewall.

Also, I'm not sure what specific things are included LMT branded ones.... But it MIGHT include TR-069 package, which also use some "disk" space.
To check see if tr069 is shown under System > Package. If so, you can uninstall that package (and can always add it back to enable LMT control of your router later).

See viewtopic.php?p=1136075

According to the specs of their site, 5g r16 has only 16mb and costs eur 485
now i understand mikrotik has newer model with 128gb flash called 5g ax

Your device only has 16mb storage.
And starting ROS7.13 or about, that became a real problem for such devices.

Netinstall is the only way out, I'm afraid.

Oh agree that it's ridiculous it comes with 16MB. And they pitch TR-069 support, which does not help when already limited space... I bet LMT is sitting on a bunch of them, only hope is they'll put pressure on MikroTik to further reduce size so it works.