diff --git a/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkActionFactory.java b/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkActionFactory.java
index 9846ee271f06dd..b2fbdd82666f4a 100644
--- a/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkActionFactory.java
+++ b/src/main/java/com/google/devtools/build/lib/analysis/starlark/StarlarkActionFactory.java
@@ -144,7 +144,7 @@ private void checkToolchainParameterIsSet(Object toolchainUnchecked) throws Eval
     if (toolchainUnchecked == Starlark.UNBOUND) {
       throw Starlark.errorf(
           "Couldn't identify if tools are from implicit dependencies or a toolchain. Please"
-              + " set the toolchain parameter.");
+              + " set the toolchain parameter. If you're not using a toolchain, set it to 'None'.");
     }
   }
 
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/AutoExecGroupsTest.java b/src/test/java/com/google/devtools/build/lib/analysis/AutoExecGroupsTest.java
index c44579070fdd28..6c61a7f84a69aa 100644
--- a/src/test/java/com/google/devtools/build/lib/analysis/AutoExecGroupsTest.java
+++ b/src/test/java/com/google/devtools/build/lib/analysis/AutoExecGroupsTest.java
@@ -186,6 +186,7 @@ private void createCustomRule(
         "  implementation = _impl,",
         "  attrs = {",
         "    '_tool': attr.label(default = '//toolchain:a_tool', cfg = 'exec', executable = True),",
+        "    '_nonexecutable_tool': attr.label(default = '//toolchain:b_tool', cfg = 'exec'),",
         extraAttributes,
         "  },",
         "  exec_groups = {",
@@ -404,6 +405,43 @@ public void toolInExecutableIdentified_noToolchainParameter_noError() throws Exc
     assertNoEvents();
   }
 
+  @Test
+  public void toolWithFilesToRunExecutable_noToolchainParameter_reportsError() throws Exception {
+    createCustomRule(
+        /* action= */ "ctx.actions.run",
+        /* actionParameters= */ "executable ="
+            + " ctx.attr._nonexecutable_tool[DefaultInfo].files_to_run.executable,",
+        /* extraAttributes= */ "",
+        /* toolchains= */ "['//rule:toolchain_type_1', '//rule:toolchain_type_2']",
+        /* execGroups= */ "",
+        /* execCompatibleWith= */ "");
+    useConfiguration("--incompatible_auto_exec_groups");
+
+    reporter.removeHandler(failFastHandler);
+    getConfiguredTarget("//test:custom_rule_name");
+
+    assertContainsEvent(
+        "Couldn't identify if tools are from implicit dependencies or a toolchain. Please set"
+            + " the toolchain parameter. If you're not using a toolchain, set it to 'None'.");
+  }
+
+  @Test
+  public void toolWithFilesToRunExecutable_toolchainParameterSetToNone_noError() throws Exception {
+    createCustomRule(
+        /* action= */ "ctx.actions.run",
+        /* actionParameters= */ "toolchain = None,"
+            + " executable = ctx.attr._nonexecutable_tool[DefaultInfo].files_to_run.executable,",
+        /* extraAttributes= */ "",
+        /* toolchains= */ "['//rule:toolchain_type_1', '//rule:toolchain_type_2']",
+        /* execGroups= */ "",
+        /* execCompatibleWith= */ "");
+    useConfiguration("--incompatible_auto_exec_groups");
+
+    getConfiguredTarget("//test:custom_rule_name");
+
+    assertNoEvents();
+  }
+
   @Test
   public void toolInExecutableUnidentified_noToolchainParameter_reportsError() throws Exception {
     createCustomRule(
@@ -420,7 +458,7 @@ public void toolInExecutableUnidentified_noToolchainParameter_reportsError() thr
 
     assertContainsEvent(
         "Couldn't identify if tools are from implicit dependencies or a toolchain. Please set"
-            + " the toolchain parameter.");
+            + " the toolchain parameter. If you're not using a toolchain, set it to 'None'.");
   }
 
   @Test
@@ -441,7 +479,7 @@ public void toolWithFilesToRunInExecutableUnidentified_noToolchainParameter_repo
 
     assertContainsEvent(
         "Couldn't identify if tools are from implicit dependencies or a toolchain. Please set"
-            + " the toolchain parameter.");
+            + " the toolchain parameter. If you're not using a toolchain, set it to 'None'.");
   }
 
   @Test
@@ -465,7 +503,7 @@ public void toolInToolsUnidentified_noToolchainParameter_reportsError(String act
 
     assertContainsEvent(
         "Couldn't identify if tools are from implicit dependencies or a toolchain. Please set"
-            + " the toolchain parameter.");
+            + " the toolchain parameter. If you're not using a toolchain, set it to 'None'.");
   }
 
   @Test
@@ -489,7 +527,7 @@ public void toolWithFilesToRunInToolsUnidentified_noToolchainParameter_reportsEr
 
     assertContainsEvent(
         "Couldn't identify if tools are from implicit dependencies or a toolchain. Please set"
-            + " the toolchain parameter.");
+            + " the toolchain parameter. If you're not using a toolchain, set it to 'None'.");
   }
 
   @Test
@@ -512,7 +550,7 @@ public void depsetInTools_noToolchainParameter_reportsError(String action) throw
 
     assertContainsEvent(
         "Couldn't identify if tools are from implicit dependencies or a toolchain. Please set"
-            + " the toolchain parameter.");
+            + " the toolchain parameter. If you're not using a toolchain, set it to 'None'.");
   }
 
   @Test