There are likely some small changes in the schema.
I would use the following flow.
backup everything create your current db clone install jsreport 2.8.0 and run it configured to the db clone test the app, it can fail on some schema errors, typically with error "missing column jsreport_TemplateType" run alter table jsreport_TemplateType <column> <datatype>, you can get the type from http://localhost:5488/odata/$metadata when everything works, you can use the same alters on your current db and update jsreport