diff --git a/src/centpkg/cli.py b/src/centpkg/cli.py
index 5ef3f19..358b950 100755
--- a/src/centpkg/cli.py
+++ b/src/centpkg/cli.py
@@ -193,7 +193,14 @@ class centpkgClient(cliClient):
                     self.log.info("Checking rhel-target information:")
                     stream_version = self.cmd.target.split('-')[0]
                     rhel_version = centpkg.utils.stream_mapping(stream_version)
-                    active_y, in_stabilization = centpkg.utils.determine_active_y_version(rhel_version, pp_api_url)
+                    try:
+                        active_y, in_stabilization = centpkg.utils.determine_active_y_version(rhel_version, pp_api_url)
+                    except AssertionError as e:
+                        self.log.info("  Error: centpkg cannot determine the development phase.")
+                        self.log.info("         Please file an issue at https://git.centos.org/centos/centpkg")
+                        self.log.info("  Workaround: Use the --rhel-target option")
+                        self.log.info("Exiting")
+                        raise SystemExit
                     divergent_branch = centpkg.utils.does_divergent_branch_exist(
                                             self.cmd.repo_name,
                                             rhel_version,