diff --git a/extensions/typescript-language-features/src/extension.browser.ts b/extensions/typescript-language-features/src/extension.browser.ts
index d3c0cbb9f83..8b6db953173 100644
--- a/extensions/typescript-language-features/src/extension.browser.ts
+++ b/extensions/typescript-language-features/src/extension.browser.ts
@@ -57,7 +57,7 @@ export function activate(
 		new TypeScriptVersion(
 			TypeScriptVersionSource.Bundled,
 			vscode.Uri.joinPath(context.extensionUri, 'dist/browser/typescript/tsserver.web.js').toString(),
-			API.fromSimpleString('4.2.0')));
+			API.fromSimpleString('4.3.5')));
 
 	const lazyClientHost = createLazyClientHost(context, false, {
 		pluginManager,
diff --git a/extensions/typescript-language-features/src/tsServer/bufferSyncSupport.ts b/extensions/typescript-language-features/src/tsServer/bufferSyncSupport.ts
index a2fe799ac62..edc458d9945 100644
--- a/extensions/typescript-language-features/src/tsServer/bufferSyncSupport.ts
+++ b/extensions/typescript-language-features/src/tsServer/bufferSyncSupport.ts
@@ -303,19 +303,26 @@ class GetErrRequest {
 	private readonly _token: vscode.CancellationTokenSource = new vscode.CancellationTokenSource();
 
 	private constructor(
-		client: ITypeScriptServiceClient,
+		private readonly client: ITypeScriptServiceClient,
 		public readonly files: ResourceMap<void>,
 		onDone: () => void
 	) {
+		if (!this.isErrorReportingEnabled()) {
+			this._done = true;
+			setImmediate(onDone);
+			return;
+		}
+
+		const supportsSyntaxGetErr = this.client.apiVersion.gte(API.v440);
 		const allFiles = coalesce(Array.from(files.entries)
-			.filter(entry => client.hasCapabilityForResource(entry.resource, ClientCapability.Semantic))
+			.filter(entry => supportsSyntaxGetErr || client.hasCapabilityForResource(entry.resource, ClientCapability.Semantic))
 			.map(entry => client.normalizedPath(entry.resource)));
 
-		if (!allFiles.length || !client.capabilities.has(ClientCapability.Semantic)) {
+		if (!allFiles.length) {
 			this._done = true;
 			setImmediate(onDone);
 		} else {
-			const request = client.configuration.enableProjectDiagnostics
+			const request = this.areProjectDiagnosticsEnabled()
 				// Note that geterrForProject is almost certainly not the api we want here as it ends up computing far
 				// too many diagnostics
 				? client.executeAsync('geterrForProject', { delay: 0, file: allFiles[0] }, this._token.token)
@@ -331,6 +338,19 @@ class GetErrRequest {
 		}
 	}
 
+	private isErrorReportingEnabled() {
+		if (this.client.apiVersion.gte(API.v440)) {
+			return true;
+		} else {
+			// Older TS versions only support `getErr` on semantic server
+			return this.client.capabilities.has(ClientCapability.Semantic);
+		}
+	}
+
+	private areProjectDiagnosticsEnabled() {
+		return this.client.configuration.enableProjectDiagnostics && this.client.capabilities.has(ClientCapability.Semantic);
+	}
+
 	public cancel(): any {
 		if (!this._done) {
 			this._token.cancel();