diff --git a/src/containerapp/azext_containerapp/custom.py b/src/containerapp/azext_containerapp/custom.py
index 58f5f65dd49..e6d003d13d6 100644
--- a/src/containerapp/azext_containerapp/custom.py
+++ b/src/containerapp/azext_containerapp/custom.py
@@ -504,6 +504,11 @@ def update_containerapp_logic(cmd,
                               from_revision=None):
     _validate_subscription_registered(cmd, CONTAINER_APPS_RP)
 
+    # Validate that max_replicas is set to 0-30
+    if max_replicas is not None:
+        if max_replicas < 1 or max_replicas > 30:
+            raise ArgumentUsageError('--max-replicas must be in the range [1,30]')
+
     if yaml:
         if image or min_replicas or max_replicas or\
            set_env_vars or remove_env_vars or replace_env_vars or remove_all_env_vars or cpu or memory or\