Pro Crash when opening new or existing file

I’ve been using a licenced version of Omnigraffle 5 (5.4.4 v139.18 t187838) for a few years without issue.
It suddenly stopped working a few weeks ago with the following crash report:

OmniGraffle Professional: objc[1512]: Class FileReference is implemented in both /System/Library/Frameworks/IOBluetooth.framework/Versions/A/IOBluetooth and /Applications/OmniGraffle Professional One of the two will be used. Which one is undefined.

OmniGraffle Professional: -[NSScriptSuiteRegistry aeteResource:] - the only supported language name is English.

OmniGraffle Professional: OSULastRunStartInterval default is non-nil; unless you forcibly killed the app and restarted it it should be nil at launch time.

I tried version 6 demo and it works fine, but I don’t want to pay again for this new version.
I tried to re-install 5, after removing all existing versions without success.
Any known solution to this issue?

I get this error to not matter what I do I can not resolve it.

Sorry to hear about the trouble. If this happened recently after upgrading to High Sierra, it may be a known issue. Apple has made changes that are not compatible with OmniGraffle 5. See for details and options.

If you are using an operating system that should be compatible with OmniGraffle 5, try and feel free to contact us if we can help further.