Steps to reproduce the issue:
1. In Gradebook: Create a gradebook entry (say Grade1).
2. In Assignment: Create an assignment (say Asn1) and associate it to Grade1.
3. Any student (say student A) submits Asn1.
4. In Gradebook: Instructor grades the student A in Grade1 with a 2 decimal point number: e.g 7.89 points.
5. In Assignment: Instructor checks the student A's grade and he's got 7.9 points in Asn1 (the score is rounded to 1 decimal point).
6. In Assignment: Instructor changes the student A's grade to 9 points and he clicks on the "Save and Release to Student" button. An error message is displayed: "Alert: Please use only one decimal place for the grade field." Therefore instructor is not able to save and release the new score.
It happens either in Gradebook or in Gradebook2. Tested in https://qa10.longsight.com/portal. I've attached an image to clarify this.