Dear Episerver developers,
at this moment we can't update CMS to v10, because EPiServer.Forms.ServiceApi blocks us to do this.
When it is planned to update it for usage with CMS10, Forms >=4.1.0.
Forms.ServiceApi has been blocked by COM-3295, but it has closed recently.
We resume working on it a few days ago, and Forms.ServiceApi 3.1 is being tested in QA.