diff --git a/src/vs/workbench/api/browser/mainThreadTerminalService.ts b/src/vs/workbench/api/browser/mainThreadTerminalService.ts
index caf04c46e88..7883f70b7b6 100644
--- a/src/vs/workbench/api/browser/mainThreadTerminalService.ts
+++ b/src/vs/workbench/api/browser/mainThreadTerminalService.ts
@@ -268,8 +268,13 @@ export class MainThreadTerminalService implements MainThreadTerminalServiceShape
 	}
 
 	private _onTerminalRequestVirtualProcess(proxy: ITerminalProcessExtHostProxy): void {
-		this._terminalProcessesReady[proxy.terminalId](proxy);
-		delete this._terminalProcessesReady[proxy.terminalId];
+		const ready = this._terminalProcessesReady[proxy.terminalId];
+		if (!ready) {
+			this._terminalProcesses[proxy.terminalId] = Promise.resolve(proxy);
+		} else {
+			ready(proxy);
+			delete this._terminalProcessesReady[proxy.terminalId];
+		}
 
 		// Note that onReisze is not being listened to here as it needs to fire when max dimensions
 		// change, excluding the dimension override
diff --git a/src/vs/workbench/api/node/extHostTerminalService.ts b/src/vs/workbench/api/node/extHostTerminalService.ts
index 744c0ca3c2c..ce45045e375 100644
--- a/src/vs/workbench/api/node/extHostTerminalService.ts
+++ b/src/vs/workbench/api/node/extHostTerminalService.ts
@@ -337,7 +337,7 @@ export class ExtHostTerminalService implements ExtHostTerminalServiceShape {
 		return terminal;
 	}
 
-	public async attachVirtualProcessToTerminal(id: number, virtualProcess: vscode.TerminalVirtualProcess): Promise<void> {
+	public attachVirtualProcessToTerminal(id: number, virtualProcess: vscode.TerminalVirtualProcess) {
 		const terminal = this._getTerminalById(id);
 		if (!terminal) {
 			throw new Error(`Cannot resolve terminal with id ${id} for virtual process`);
@@ -411,7 +411,7 @@ export class ExtHostTerminalService implements ExtHostTerminalServiceShape {
 			}
 			return;
 		}
-		this._performTerminalIdAction(id, terminal => {
+		this.performTerminalIdAction(id, terminal => {
 			if (terminal) {
 				this._activeTerminal = terminal;
 				if (original !== this._activeTerminal) {
@@ -496,10 +496,10 @@ export class ExtHostTerminalService implements ExtHostTerminalServiceShape {
 	}
 
 	public $acceptTerminalProcessId(id: number, processId: number): void {
-		this._performTerminalIdAction(id, terminal => terminal._setProcessId(processId));
+		this.performTerminalIdAction(id, terminal => terminal._setProcessId(processId));
 	}
 
-	private _performTerminalIdAction(id: number, callback: (terminal: ExtHostTerminal) => void): void {
+	public performTerminalIdAction(id: number, callback: (terminal: ExtHostTerminal) => void): void {
 		let terminal = this._getTerminalById(id);
 		if (terminal) {
 			callback(terminal);