ok, found this fixed bug, Quan, how do get this patch without upgrading to 8.10? I can't not update now, i will just have new bugs on new features.
Unfortunately there'll be now way to apply the fix without upgrading to 8.10 - this is from core assembly so no workaround is available.
What's the issue which make you can't update now?
I have cms version 7.19.2, so i have to go up to version 8... and it contains a lot of breaking changes which i don't have the time to implement.
Or is it safe to just update EPiServer.Commerce.Core 8.10.0 Package with 7.19.2 you think?
Unfortunately, no. It'll require at least CMS 8.0.
I think the biggest breaking change in CMS 8.0 was the language handling - did you try to upgrade to see how much work is needed? Generally we will recommend to upgrade to latest version as soon as possible.