diff --git a/source/reference/current-op.txt b/source/reference/current-op.txt
index 52006b460f0..e908cc2c186 100644
--- a/source/reference/current-op.txt
+++ b/source/reference/current-op.txt
@@ -79,9 +79,14 @@ Operations
 
 You can use the :method:`db.killOp()` in conjunction with the
 :data:`~currentOp.opid` field to terminate a currently running
-operation. Consider the following JavaScript operations for the
-:program:`mongo` shell that you can use to filter the output of
-identify specific types of operations:
+operation.
+
+.. note:: You cannot use :method:`db.killOp()` to kill a foreground
+   index build.
+
+The following JavaScript operations for the
+:program:`mongo` shell filter the output of
+specific types of operations:
 
 .. include:: /includes/example-filter-current-op.rst
 
@@ -97,6 +102,9 @@ depending on the kind of operation and its state.
    :method:`db.killOp()` in the :program:`mongo` shell to terminate the
    operation.
 
+   .. note:: You cannot use :method:`db.killOp()` to kill a foreground
+      index build.
+
 .. data:: currentOp.active
 
    A boolean value, that is ``true`` if the operation has started
diff --git a/source/reference/limits.txt b/source/reference/limits.txt
index 28d06a83cb0..29bd996cd4f 100644
--- a/source/reference/limits.txt
+++ b/source/reference/limits.txt
@@ -141,6 +141,12 @@ Operations
 
    .. see:: :operator:`$or` and :doc:`/core/geospatial-indexes`.
 
+.. _cannot-kill-foreground:
+.. limit:: Cannot Kill Foreground Index Build
+
+   You cannot use :method:`db.killOp()` to kill a foreground index
+   build.
+
 Naming Restrictions
 ~~~~~~~~~~~~~~~~~~~
 
diff --git a/source/reference/method/db.killOp.txt b/source/reference/method/db.killOp.txt
index 04857cbf6bc..51457db74d7 100644
--- a/source/reference/method/db.killOp.txt
+++ b/source/reference/method/db.killOp.txt
@@ -13,4 +13,7 @@ db.killOp()
    :doc:`/reference/current-op` for full documentation of the output
    of :method:`db.currentOp()`.
 
+   .. note:: You cannot use :method:`db.killOp()` to kill a foreground
+      index build.
+
    .. include:: /includes/warning-terminating-operations.rst