runtime: fail when a poststop hook fails

config.md

@@ -634,7 +634,8 @@ The `poststart` hooks MUST be executed in the [runtime namespace](glossary.md#ru
 
 ### <a name="configHooksPoststop" />Poststop
 
-The `poststop` hooks MUST be called [after the container is deleted](runtime.md#lifecycle) but before the [`delete`](runtime.md#delete) operation returns.
+The `poststop` hooks MUST be called [after the user-specified process is killed](runtime.md#lifecycle), but before the [`delete`](runtime.md#delete) operation return.
+Runtime should make sure that if a `poststop` hook failed, the [`delete`](runtime.md#delete) operation could fail and be retried.
 Cleanup or debugging functions are examples of such a hook.
 
 The `poststop` hooks' path MUST resolve in the [runtime namespace](glossary.md#runtime-namespace).

runtime.md

@@ -76,7 +76,7 @@ The lifecycle describes the timeline of events that happen from when a container
 11. Runtime's [`delete`](runtime.md#delete) command is invoked with the unique identifier of the container.
 12. The container MUST be destroyed by undoing the steps performed during create phase (step 2).
 13. The [`poststop` hooks](config.md#poststop) MUST be invoked by the runtime.
-    If any `poststop` hook fails, the runtime MUST [log a warning](#warnings), but the remaining hooks and lifecycle continue as if the hook had succeeded.
+    If any `poststop` hook fails,  the runtime MUST [generate an error](#errors), so that the Runtime's [`delete`](runtime.md#delete) command fails and retry is required until all `poststop` hooks succeed.
 
 ## <a name="runtimeErrors" />Errors