As part of the company's efforts to keep Android users safe, Google has decided to no longer allow sign-in on services like Gmail, Maps, or YouTube for devices still stuck with versions up to 2.3.7 of its mobile operating system. Fortunately, devices on Android 3.0 and later will remain on the safe side.
https://www.notebookcheck.net/Google-will-drop-devices-still-on-Android-2-3-7-and-earlier-in-September.553033.0.html