Hi i tried updating my desktop version on mac but it keeps giving me an error message. can anyone help please. 
When exactly did you get this error? What precisely did you do?
It looks like you are trying to open the index file rather than your business file.
Also, did you follow the instructions in the Guide on updating under macOS?
@Tut I tried updating to the current version 20.10.89 on mac. I followed all the guide concerning update on mac but keeps giving me this message when i open the app. i have uninstalled the older version and have downloaded the new version from your website but it the same issue once again.
@KwesiBiney, you did not answer my questions. When did you get the error? During installation? When first launching the application? While trying to open a business from the Businesses page? Some time after a business was opened and you tried to enter a transaction? While trying to open a business file, such as a backup, directly, without first launching the program? While doing something inside your application data folder? The possibilities are many and neither I nor anyone else can help without the requested information.
Also, if you read the Guide, you know that uninstalling the older version is unnecessary and a waste of time.
@Tut, the error occurred during the installation of the new version of the application please. concerning the older version, i have the application and when i tried to re-install, it also gave me this error message. 
I am currently confused as to what to do.
regards.
This is difficult to believe. Installation or updating on a Mac involves nothing more than dragging the Manager icon to your Applications folder. Your error message clearly occurred while trying to open something. I encourage you to read the Guide on updating under macOS again. Make sure you are following the instructions exactly. When properly installed, you should be able to launch the application and have your business(es) show on the Businesses page and open them from there.