diff --git a/spring-batch-docs/src/main/asciidoc/domain.adoc b/spring-batch-docs/src/main/asciidoc/domain.adoc
index c544b1053..10f78d428 100644
--- a/spring-batch-docs/src/main/asciidoc/domain.adoc
+++ b/spring-batch-docs/src/main/asciidoc/domain.adoc
@@ -557,6 +557,12 @@ As noted in the comment, `ecStep` does not equal `ecJob`. They are two different
 `ExecutionContexts`. The one scoped to the `Step` is saved at every commit point in the
 `Step`, whereas the one scoped to the Job is saved in between every `Step` execution.
 
+NOTE: In the `ExecutionContext`, all non-transient entries must be `Serializable`.
+Proper serialization of the execution context underpins the restart capability of steps and jobs.
+Should you use keys or values that are not natively serializable, you are required to
+employ a tailored serialization approach. Failing to serialize the execution context
+may jeopardize the state persistence process, making failed jobs impossible to recover properly.
+
 === JobRepository
 
 `JobRepository` is the persistence mechanism for all of the stereotypes mentioned earlier.
diff --git a/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/ExecutionContext.java b/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/ExecutionContext.java
index 49f0d348f..393e31da4 100644
--- a/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/ExecutionContext.java
+++ b/spring-batch-infrastructure/src/main/java/org/springframework/batch/item/ExecutionContext.java
@@ -29,8 +29,9 @@ import org.springframework.lang.Nullable;
  * that allows optionally for type safety on reads. It also allows for dirty checking by
  * setting a 'dirty' flag whenever any put is called.
  * <p>
- * Note that putting <code>null</code> value is equivalent to removing the entry for the
- * given key.
+ * Non-transient entries should be serializable, otherwise a custom serializer should be
+ * used. Note that putting <code>null</code> value is equivalent to removing the entry for
+ * the given key.
  *
  * @author Lucas Ward
  * @author Douglas Kaminsky