diff --git a/src/configurationProvider.ts b/src/configurationProvider.ts
index 86d8d11..ce322ce 100644
--- a/src/configurationProvider.ts
+++ b/src/configurationProvider.ts
@@ -34,7 +34,7 @@ export class JavaDebugConfigurationProvider implements vscode.DebugConfiguration
         return vscode.window.withProgress({location: vscode.ProgressLocation.Window}, (p) => {
             return new Promise((resolve, reject) => {
                 p.report({message: "Auto generating configuration..."});
-                resolveMainClass(folder.uri).then((res: any[]) => {
+                resolveMainClass(folder ? folder.uri : undefined).then((res: any[]) => {
                     let cache;
                     cache = {};
                     const launchConfigs = res.map((item) => {
@@ -86,20 +86,22 @@ export class JavaDebugConfigurationProvider implements vscode.DebugConfiguration
                 await updateDebugSettings();
             }
 
-            try {
-                const buildResult = await vscode.commands.executeCommand(commands.JAVA_BUILD_WORKSPACE);
-                console.log(buildResult);
-            } catch (err) {
-                vscode.window.showErrorMessage("Build failed, please fix build error first.");
-                return config;
-            }
-
             if (Object.keys(config).length === 0) { // No launch.json in current workspace.
                 // check whether it is opened as a folder
                 if (folder !== undefined) {
                     // for opened with folder, return directly.
                     return config;
                 }
+                // only rebuild for single file case before the build error issue is resolved.
+                try {
+                    const buildResult = await vscode.commands.executeCommand(commands.JAVA_BUILD_WORKSPACE, false);
+                    console.log(buildResult);
+                } catch (err) {
+                    const ans = await vscode.window.showErrorMessage("Build failed, do you want to continue?", "Proceed", "Abort");
+                    if (ans !== "Proceed") {
+                        return undefined;
+                    }
+                }
                 // Generate config in memory for single file
                 config.type = "java";
                 config.name = "Java Debug";
@@ -111,7 +113,7 @@ export class JavaDebugConfigurationProvider implements vscode.DebugConfiguration
 
             if (config.request === "launch") {
                 if (!config.mainClass) {
-                    const res = <any[]>(await resolveMainClass(folder.uri));
+                    const res = <any[]>(await resolveMainClass(folder ? folder.uri : undefined));
                     if (res.length === 0) {
                         vscode.window.showErrorMessage(
                             "Cannot resolve main class automatically, please specify the mainClass " +
@@ -223,7 +225,10 @@ function resolveClasspath(mainClass, projectName) {
 }
 
 function resolveMainClass(workspaceUri: vscode.Uri) {
-    return commands.executeJavaLanguageServerCommand(commands.JAVA_RESOLVE_MAINCLASS, workspaceUri.toString());
+    if (workspaceUri) {
+        return commands.executeJavaLanguageServerCommand(commands.JAVA_RESOLVE_MAINCLASS, workspaceUri.toString());
+    }
+    return commands.executeJavaLanguageServerCommand(commands.JAVA_RESOLVE_MAINCLASS);
 }
 
 async function updateDebugSettings() {