You can most certainly try, but I wouldn't recommend you do.
Sometimes Atlassian removes deprecated methods, or they change a bit of the innerworks. This could result into errors, and most importantly we wouldn't support any issues, or be responsible for anything that happens to your instance if your product version is not supported.
This sounds like you have upgraded your Bitbucket instance without checking compatibility, if that is the case, I would recommend you restore your backup if it is not much hassle.
I once again would not suggest you enable or try to enable an addon not supported by your current version.
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