diff --git a/src/vs/workbench/api/browser/mainThreadDebugService.ts b/src/vs/workbench/api/browser/mainThreadDebugService.ts
index 3b49ec144f546b3ead643c7e3359675c26365388..721187994a6ac8be8c3c7038b2bd1bb21dd74a1e 100644
--- a/src/vs/workbench/api/browser/mainThreadDebugService.ts
+++ b/src/vs/workbench/api/browser/mainThreadDebugService.ts
@@ -378,7 +378,6 @@ class ExtensionHostDebugAdapter extends AbstractDebugAdapter {
 	}
 
 	public stopSession(): Promise<void> {
-		this.cancelPending();
 		return Promise.resolve(this._proxy.$stopDASession(this._handle));
 	}
 }
diff --git a/src/vs/workbench/contrib/debug/browser/rawDebugSession.ts b/src/vs/workbench/contrib/debug/browser/rawDebugSession.ts
index db008ccaba7d0e68b42946fa1971ddcde65985a5..28e19bf76684f4bc91ca1c764c8ac1f28078faaa 100644
--- a/src/vs/workbench/contrib/debug/browser/rawDebugSession.ts
+++ b/src/vs/workbench/contrib/debug/browser/rawDebugSession.ts
@@ -112,6 +112,8 @@ export class RawDebugSession implements IDisposable {
 			}
 		}));
 
+		this.toDispose.push(this.onDidContinued(() => this.cancelPendingRequests()));
+
 		this.debugAdapter.onEvent(event => {
 			switch (event.event) {
 				case 'initialized':
@@ -466,13 +468,16 @@ export class RawDebugSession implements IDisposable {
 		return Promise.reject(new Error('goto is not supported'));
 	}
 
+	cancel(args: DebugProtocol.CancelArguments): Promise<DebugProtocol.CancelResponse> {
+		return this.send('cancel', args);
+	}
+
 	custom(request: string, args: any): Promise<DebugProtocol.Response> {
 		return this.send(request, args);
 	}
 
 	//---- private
 
-
 	private shutdown(error?: Error, restart = false): Promise<any> {
 		if (!this.inShutdown) {
 			this.inShutdown = true;
@@ -489,10 +494,23 @@ export class RawDebugSession implements IDisposable {
 		return Promise.resolve(undefined);
 	}
 
+	private cancelPendingRequests(): void {
+		if (this.debugAdapter) {
+			if (this.capabilities.supportsCancelRequest) {
+				this.debugAdapter.getPendingRequestIds().forEach(requestId => {
+					this.cancel({ requestId });
+				});
+			} else {
+				this.debugAdapter.cancelPendingRequests();
+			}
+		}
+	}
+
 	private stopAdapter(error?: Error): Promise<any> {
 		if (this.debugAdapter) {
 			const da = this.debugAdapter;
 			this.debugAdapter = null;
+			this.cancelPendingRequests();
 			return da.stopSession().then(_ => {
 				this.debugAdapterStopped = true;
 				this.fireAdapterExitEvent(error);
diff --git a/src/vs/workbench/contrib/debug/common/abstractDebugAdapter.ts b/src/vs/workbench/contrib/debug/common/abstractDebugAdapter.ts
index 5d01d78a039b9fa28cde34c4d722c64c1c98f56a..f288628f314314644dcf749015f204e90e7c67b2 100644
--- a/src/vs/workbench/contrib/debug/common/abstractDebugAdapter.ts
+++ b/src/vs/workbench/contrib/debug/common/abstractDebugAdapter.ts
@@ -137,11 +137,10 @@ export abstract class AbstractDebugAdapter implements IDebugAdapter {
 		this.sendMessage(message);
 	}
 
-	async cancelPending(): Promise<void> {
+	async cancelPendingRequests(): Promise<void> {
 		const pending = new Map<number, (e: DebugProtocol.Response) => void>();
 		this.pendingRequests.forEach((value, key) => pending.set(key, value));
-		this.pendingRequests.clear();
-		await timeout(1000);
+		await timeout(500);
 		pending.forEach((callback, request_seq) => {
 			const err: DebugProtocol.Response = {
 				type: 'response',
@@ -152,10 +151,15 @@ export abstract class AbstractDebugAdapter implements IDebugAdapter {
 				message: 'canceled'
 			};
 			callback(err);
+			this.pendingRequests.delete(request_seq);
 		});
 	}
 
+	getPendingRequestIds(): number[] {
+		return Array.from(this.pendingRequests.keys());
+	}
+
 	dispose(): void {
-		this.cancelPending();
+		// noop
 	}
 }
diff --git a/src/vs/workbench/contrib/debug/common/debug.ts b/src/vs/workbench/contrib/debug/common/debug.ts
index f146ee3ca151ac3fd86d7d3ea86173fe0d985b12..7900963c47c962c529a68d2f52084eba79ae519b 100644
--- a/src/vs/workbench/contrib/debug/common/debug.ts
+++ b/src/vs/workbench/contrib/debug/common/debug.ts
@@ -506,6 +506,8 @@ export interface IDebugAdapter extends IDisposable {
 	sendResponse(response: DebugProtocol.Response): void;
 	sendRequest(command: string, args: any, clb: (result: DebugProtocol.Response) => void, timeout?: number): void;
 	stopSession(): Promise<void>;
+	cancelPendingRequests(): void;
+	getPendingRequestIds(): number[];
 }
 
 export interface IDebugAdapterFactory extends ITerminalLauncher {
diff --git a/src/vs/workbench/contrib/debug/node/debugAdapter.ts b/src/vs/workbench/contrib/debug/node/debugAdapter.ts
index 3a8e1feb93a8030bd3ee0d6fa12c9cd6b74e7080..c13409c0603ecbc05d9550b1305ec0c4642a1cfd 100644
--- a/src/vs/workbench/contrib/debug/node/debugAdapter.ts
+++ b/src/vs/workbench/contrib/debug/node/debugAdapter.ts
@@ -129,9 +129,6 @@ export class SocketDebugAdapter extends StreamDebugAdapter {
 
 	stopSession(): Promise<void> {
 
-		// Cancel all sent promises on disconnect so debug trees are not left in a broken state #3666.
-		this.cancelPending();
-
 		if (this.socket) {
 			this.socket.end();
 			this.socket = undefined;
@@ -254,9 +251,6 @@ export class ExecutableDebugAdapter extends StreamDebugAdapter {
 
 	stopSession(): Promise<void> {
 
-		// Cancel all sent promises on disconnect so debug trees are not left in a broken state #3666.
-		this.cancelPending();
-
 		if (!this.serverProcess) {
 			return Promise.resolve(undefined);
 		}