diff --git a/src/vs/workbench/api/browser/mainThreadTask.ts b/src/vs/workbench/api/browser/mainThreadTask.ts
index 9e5763d0614..e904b50d182 100644
--- a/src/vs/workbench/api/browser/mainThreadTask.ts
+++ b/src/vs/workbench/api/browser/mainThreadTask.ts
@@ -264,7 +264,7 @@ namespace TaskSourceDTO {
 			}
 		} else if (value.kind === TaskSourceKind.Workspace) {
 			result.extensionId = '$core';
-			result.scope = value.config.workspaceFolder.uri;
+			result.scope = value.config.workspaceFolder ? value.config.workspaceFolder.uri : TaskScope.Global;
 		}
 		return result;
 	}
diff --git a/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts b/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts
index 23fbb2cbd15..6a3efa5fd4b 100644
--- a/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts
+++ b/src/vs/workbench/contrib/tasks/browser/abstractTaskService.ts
@@ -983,7 +983,12 @@ export abstract class AbstractTaskService extends Disposable implements ITaskSer
 	private getResourceForTask(task: CustomTask): URI {
 		let uri = this.getResourceForKind(task._source.kind);
 		if (!uri) {
-			uri = task.getWorkspaceFolder().toResource(task._source.config.file);
+			const taskFolder = task.getWorkspaceFolder();
+			if (taskFolder) {
+				uri = taskFolder.toResource(task._source.config.file);
+			} else {
+				uri = this.workspaceFolders[0].uri;
+			}
 		}
 		return uri;
 	}
diff --git a/src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts b/src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts
index ce5593930c6..1c45953acdf 100644
--- a/src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts
+++ b/src/vs/workbench/contrib/tasks/browser/terminalTaskSystem.ts
@@ -462,7 +462,14 @@ export class TerminalTaskSystem implements ITaskSystem {
 	}
 
 	private executeCommand(task: CustomTask | ContributedTask, trigger: string): Promise<ITaskSummary> {
-		const workspaceFolder = this.currentTask.workspaceFolder = task.getWorkspaceFolder();
+		const taskWorkspaceFolder = task.getWorkspaceFolder();
+		let workspaceFolder: IWorkspaceFolder | undefined;
+		if (taskWorkspaceFolder) {
+			workspaceFolder = this.currentTask.workspaceFolder = taskWorkspaceFolder;
+		} else {
+			const folders = this.contextService.getWorkspace().folders;
+			workspaceFolder = folders.length > 0 ? folders[0] : undefined;
+		}
 		const systemInfo: TaskSystemInfo | undefined = this.currentTask.systemInfo = workspaceFolder ? this.taskSystemInfoResolver(workspaceFolder) : undefined;
 
 		let variables = new Set<string>();
diff --git a/src/vs/workbench/contrib/tasks/common/tasks.ts b/src/vs/workbench/contrib/tasks/common/tasks.ts
index 0737e5fea02..760c3f67664 100644
--- a/src/vs/workbench/contrib/tasks/common/tasks.ts
+++ b/src/vs/workbench/contrib/tasks/common/tasks.ts
@@ -380,7 +380,7 @@ export namespace TaskSourceKind {
 }
 
 export interface TaskSourceConfigElement {
-	workspaceFolder: IWorkspaceFolder;
+	workspaceFolder?: IWorkspaceFolder;
 	workspace?: IWorkspace;
 	file: string;
 	index: number;
@@ -728,7 +728,7 @@ export class CustomTask extends CommonTask {
 		return JSON.stringify(key);
 	}
 
-	public getWorkspaceFolder(): IWorkspaceFolder {
+	public getWorkspaceFolder(): IWorkspaceFolder | undefined {
 		return this._source.config.workspaceFolder;
 	}