1 files changed, 4 insertions, 0 deletions
diff --git a/src/main/java/com/google/devtools/build/lib/sandbox/SandboxActionContextProvider.java b/src/main/java/com/google/devtools/build/lib/sandbox/SandboxActionContextProvider.java
index 1efa8912a5..c8c0ab522b 100644
--- a/src/main/java/com/google/devtools/build/lib/sandbox/SandboxActionContextProvider.java
+++ b/src/main/java/com/google/devtools/build/lib/sandbox/SandboxActionContextProvider.java
@@ -72,6 +72,10 @@ final class SandboxActionContextProvider extends ActionContextProvider {
                   env.getDirectories(),
                   verboseFailures,
                   env.getRuntime().getProductName()));
+        } else {
+          if (!buildRequest.getOptions(SandboxOptions.class).ignoreUnsupportedSandboxing) {
+            env.getReporter().handle(Event.warn(SANDBOX_NOT_SUPPORTED_MESSAGE));
+          }
         }
         break;
       default: