diff --git a/jupyter_server/_version.py b/jupyter_server/_version.py
index 6cfed5bac1..5addcf85d5 100644
--- a/jupyter_server/_version.py
+++ b/jupyter_server/_version.py
@@ -6,7 +6,7 @@
 from typing import List
 
 # Version string must appear intact for automatic versioning
-__version__ = "2.9.1"
+__version__ = "2.10.0.dev0"
 
 # Build up version_info tuple for backwards compatibility
 pattern = r"(?P<major>\d+).(?P<minor>\d+).(?P<patch>\d+)(?P<rest>.*)"