Bookkeeper & I can't open each other's files

I’m using Manager Version 20.2.52. on a Mac El Capitan.
Until recently, my bookkeeper and I were able to exchange data files easily.
He uses Manager on Windows.
Lately, when he returns my edited file to me, I get this error message:
Internal Error
Manager.Upgrade+UpgradeException: Schema: 233 > 232
** at Manager.Upgrade.Process (System.Guid fileId) [0x00249] in :0 **
** at Manager.ApplicationData.Get (System.Guid entityId) [0x00160] in :0 **
** at ManagerServer.HttpHandler.ProcessRequest () [0x004f5] in <4aa5772b65244dc6980a481b6f4f93b7>:0**

Does anyone know how to fix this?

Yes, upgrade to the latest version. Not sure why you don’t get proper error message. I will need to check that but upgrading to the latest version will fix that issue.

Thanks Lubos, I will try that.
I believed I was using the latest version.