Hi,
i have a hAP Lite in production use. But i cannot upgrade (or downgrade) it because there is not enough free space.
Look at the attached picture. There is no additional packages, no files, but my free space is only 4,5 MB. The base router os package is 4,9 Mb. I cannot upload it to update only the base packages (as i read on forums this is the only solution to update such hardware…)
Because this router is in production use, i cannot do a netinstall, os something like that.
Please help!
If you do an update via internet using the “check for updates” instead of uploading the file, it will probably work.
At least this was stated by MT: It will download the update into RAM and overwrite the current firmware, without the need of flash space.
Even with check for updates it shows error in status bar about low disk space. I think the only way is to backup configuration, logs, certificates etc and reset the router. I think the problem is due to mikrotik’s latest wireless packages swap tricks that consume extra space.
Offtopic: do you really use “release candidates” in production? 
You have somehow deleted the “/flash” directory, where all the uploads should go. Then you could upload also manually.