Georgina, If the earlier version was 2.6.x ( use Help->About to check the version running) and the version on Mojave is V3.x, there is a file conversion which should be run the first time you open the data file. Most of it is related to changes in the locations of configuration files but there may have been some file conversion. That you can open the file on an earlier version indicates this has not happened as you should not be able to open the file with a 2.6.x version once it has been converted to run with v3.
https://wiki.gnucash.org/wiki/Configuration_Locations gives the locations for the configuration files for all 3 Operating systems. the locations labelled as MacOS. If you have no files in the config locations listed for v3 and there are files in the locations listed for V2.6 then it is likely the conversion won't have happened. I don't use MacOS but know some users have experienced difficulty with initially running v3. If you look back through the user mailing list archives "http://gnucash.1415818.n4.nabble.com/template/NamlServlet.jtp?macro=search_page&node=1415818&query=MacOS+++Gnucash+won%27t+open&days=180" you should throw up some posts which should have some useful details and solutions. Failing that one of the MacOS users may reply. Good luck David Cousens ----- David Cousens -- Sent from: http://gnucash.1415818.n4.nabble.com/GnuCash-User-f1415819.html _______________________________________________ gnucash-user mailing list gnucash-user@gnucash.org To update your subscription preferences or to unsubscribe: https://lists.gnucash.org/mailman/listinfo/gnucash-user If you are using Nabble or Gmane, please see https://wiki.gnucash.org/wiki/Mailing_Lists for more information. ----- Please remember to CC this list on all your replies. You can do this by using Reply-To-List or Reply-All.