diff --git a/src/vs/workbench/contrib/debug/browser/debugSession.ts b/src/vs/workbench/contrib/debug/browser/debugSession.ts
index b368e7026f86e04da00d48e1d47f6934cd222a98..dcedf0a95e2f638442345bd03db23191cf665f41 100644
--- a/src/vs/workbench/contrib/debug/browser/debugSession.ts
+++ b/src/vs/workbench/contrib/debug/browser/debugSession.ts
@@ -381,6 +381,10 @@ export class DebugSession implements IDebugSession {
 		if (this.raw) {
 			const source = this.getRawSource(uri);
 			const response = await this.raw.breakpointLocations({ source, line: lineNumber });
+			if (!response.body || !response.body.breakpoints) {
+				return [];
+			}
+
 			const positions = response.body.breakpoints.map(bp => ({ lineNumber: bp.line, column: bp.column || 1 }));
 
 			return distinct(positions, p => `${p.lineNumber}:${p.column}`);