diff --git a/Extension/src/LanguageServer/protocolFilter.ts b/Extension/src/LanguageServer/protocolFilter.ts
index 0a166df83..d6462072e 100644
--- a/Extension/src/LanguageServer/protocolFilter.ts
+++ b/Extension/src/LanguageServer/protocolFilter.ts
@@ -45,8 +45,10 @@ export function createProtocolFilter(): Middleware {
                     // client.takeOwnership() will call client.TrackedDocuments.add() again, but that's ok. It's a Set.
                     client.takeOwnership(document);
                     void sendMessage(document);
-                    const cppEditors: vscode.TextEditor[] = vscode.window.visibleTextEditors.filter(e => util.isCpp(e.document));
-                    client.onDidChangeVisibleTextEditors(cppEditors).catch(logAndReturn.undefined);
+                    client.ready.then(() => {
+                        const cppEditors: vscode.TextEditor[] = vscode.window.visibleTextEditors.filter(e => util.isCpp(e.document));
+                        client.onDidChangeVisibleTextEditors(cppEditors).catch(logAndReturn.undefined);
+                    }).catch(logAndReturn.undefined);
                 }
             }
         },
diff --git a/Extension/test/scenarios/SingleRootProject/tests/lmTool.test.ts b/Extension/test/scenarios/SingleRootProject/tests/lmTool.test.ts
index 3b45b308e..52d062a40 100644
--- a/Extension/test/scenarios/SingleRootProject/tests/lmTool.test.ts
+++ b/Extension/test/scenarios/SingleRootProject/tests/lmTool.test.ts
@@ -72,6 +72,7 @@ describe('CppConfigurationLanguageModelTool Tests', () => {
             this.isClosed = isClosed;
             this.eol = eol;
             this.lineCount = lineCount;
+            this.encoding = '';
         }
         fileName: string;
         isUntitled: boolean;
@@ -79,6 +80,7 @@ describe('CppConfigurationLanguageModelTool Tests', () => {
         version: number;
         isDirty: boolean;
         isClosed: boolean;
+        encoding: string;
         save(): Thenable<boolean> {
             throw new Error('Method not implemented.');
         }