diff --git a/android/paths.go b/android/paths.go
index 5eeb6e5..2e378ba 100644
--- a/android/paths.go
+++ b/android/paths.go
@@ -263,7 +263,8 @@
 
 // OptionalPath is a container that may or may not contain a valid Path.
 type OptionalPath struct {
-	path Path // nil if invalid.
+	path          Path   // nil if invalid.
+	invalidReason string // Not applicable if path != nil. "" if the reason is unknown.
 }
 
 // OptionalPathForPath returns an OptionalPath containing the path.
@@ -271,6 +272,12 @@
 	return OptionalPath{path: path}
 }
 
+// InvalidOptionalPath returns an OptionalPath that is invalid with the given reason.
+func InvalidOptionalPath(reason string) OptionalPath {
+
+	return OptionalPath{invalidReason: reason}
+}
+
 // Valid returns whether there is a valid path
 func (p OptionalPath) Valid() bool {
 	return p.path != nil
@@ -280,11 +287,26 @@
 // there is a valid path, since this method will panic if there is not.
 func (p OptionalPath) Path() Path {
 	if p.path == nil {
-		panic("Requesting an invalid path")
+		msg := "Requesting an invalid path"
+		if p.invalidReason != "" {
+			msg += ": " + p.invalidReason
+		}
+		panic(msg)
 	}
 	return p.path
 }
 
+// InvalidReason returns the reason that the optional path is invalid, or "" if it is valid.
+func (p OptionalPath) InvalidReason() string {
+	if p.path != nil {
+		return ""
+	}
+	if p.invalidReason == "" {
+		return "unknown"
+	}
+	return p.invalidReason
+}
+
 // AsPaths converts the OptionalPath into Paths.
 //
 // It returns nil if this is not valid, or a single length slice containing the Path embedded in
@@ -1073,6 +1095,7 @@
 	path, err := pathForSource(ctx, pathComponents...)
 	if err != nil {
 		reportPathError(ctx, err)
+		// No need to put the error message into the returned path since it has been reported already.
 		return OptionalPath{}
 	}
 
@@ -1087,7 +1110,7 @@
 		return OptionalPath{}
 	}
 	if !exists {
-		return OptionalPath{}
+		return InvalidOptionalPath(path.String() + " does not exist")
 	}
 	return OptionalPathForPath(path)
 }
@@ -1123,6 +1146,7 @@
 		relDir = srcPath.path
 	} else {
 		ReportPathErrorf(ctx, "Cannot find relative path for %s(%s)", reflect.TypeOf(path).Name(), path)
+		// No need to put the error message into the returned path since it has been reported already.
 		return OptionalPath{}
 	}
 	dir := filepath.Join(p.srcDir, p.path, relDir)
@@ -1136,7 +1160,7 @@
 		return OptionalPath{}
 	}
 	if len(paths) == 0 {
-		return OptionalPath{}
+		return InvalidOptionalPath(dir + " does not exist")
 	}
 	relPath := Rel(ctx, p.srcDir, paths[0])
 	return OptionalPathForPath(PathForSource(ctx, relPath))
diff --git a/android/paths_test.go b/android/paths_test.go
index f4e4ce1..3f4625d 100644
--- a/android/paths_test.go
+++ b/android/paths_test.go
@@ -137,26 +137,35 @@
 
 func TestOptionalPath(t *testing.T) {
 	var path OptionalPath
-	checkInvalidOptionalPath(t, path)
+	checkInvalidOptionalPath(t, path, "unknown")
 
 	path = OptionalPathForPath(nil)
-	checkInvalidOptionalPath(t, path)
+	checkInvalidOptionalPath(t, path, "unknown")
+
+	path = InvalidOptionalPath("foo")
+	checkInvalidOptionalPath(t, path, "foo")
+
+	path = InvalidOptionalPath("")
+	checkInvalidOptionalPath(t, path, "unknown")
 
 	path = OptionalPathForPath(PathForTesting("path"))
 	checkValidOptionalPath(t, path, "path")
 }
 
-func checkInvalidOptionalPath(t *testing.T, path OptionalPath) {
+func checkInvalidOptionalPath(t *testing.T, path OptionalPath, expectedInvalidReason string) {
 	t.Helper()
 	if path.Valid() {
-		t.Errorf("Uninitialized OptionalPath should not be valid")
+		t.Errorf("Invalid OptionalPath should not be valid")
+	}
+	if path.InvalidReason() != expectedInvalidReason {
+		t.Errorf("Wrong invalid reason: expected %q, got %q", expectedInvalidReason, path.InvalidReason())
 	}
 	if path.String() != "" {
-		t.Errorf("Uninitialized OptionalPath String() should return \"\", not %q", path.String())
+		t.Errorf("Invalid OptionalPath String() should return \"\", not %q", path.String())
 	}
 	paths := path.AsPaths()
 	if len(paths) != 0 {
-		t.Errorf("Uninitialized OptionalPath AsPaths() should return empty Paths, not %q", paths)
+		t.Errorf("Invalid OptionalPath AsPaths() should return empty Paths, not %q", paths)
 	}
 	defer func() {
 		if r := recover(); r == nil {
@@ -171,6 +180,9 @@
 	if !path.Valid() {
 		t.Errorf("Initialized OptionalPath should not be invalid")
 	}
+	if path.InvalidReason() != "" {
+		t.Errorf("Initialized OptionalPath should not have an invalid reason, got: %q", path.InvalidReason())
+	}
 	if path.String() != expectedString {
 		t.Errorf("Initialized OptionalPath String() should return %q, not %q", expectedString, path.String())
 	}