In case we use -Xshare:on with additional flags (regarding coh or coops) and we have the corresponding jsa archive not present,
we get this message/error :

Error occurred during initialization of VM
Unable to use shared archive.

Maybe the error message could be a little improved, e.g. telling what jsa file is not present or even how to generate it?
For example

Error occurred during initialization of VM
Unable to use jsa shared archive, classes_nocoops_coh.jsa is not present.