Backend Error: Unknown Error [At loading screen]

Unable to start the game due to Backend Error: Unknown Error at first loading screen (one with spruce).

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Looking for solution.

Quote from kikirio

This is due to the game version, current AKI is compatible with 0.12.10.2.12646 you will need to wait for an update.

Is there a way to somehow downgrade version or to replace key files with older ones?

Updated server to 1.5.1
Everything works fine so far.

Issue solved.