diff --git a/src/features/inlay-hints.ts b/src/features/inlay-hints.ts
index 4a273aa4..d1d3f350 100644
--- a/src/features/inlay-hints.ts
+++ b/src/features/inlay-hints.ts
@@ -34,21 +34,21 @@ export class TypeScriptInlayHintsProvider {
         token?: lsp.CancellationToken,
     ): Promise<lsp.InlayHint[]> {
         if (tspClient.apiVersion.lt(TypeScriptInlayHintsProvider.minVersion)) {
-            lspClient.showErrorMessage('Inlay Hints request failed. Requires TypeScript 4.4+.');
+            lspClient.showWarningMessage('Inlay Hints request failed. Requires TypeScript 4.4+.');
             return [];
         }
 
         const file = uriToPath(uri);
 
         if (!file) {
-            lspClient.showErrorMessage('Inlay Hints request failed. No resource provided.');
+            lspClient.showWarningMessage('Inlay Hints request failed. No resource provided.');
             return [];
         }
 
         const document = documents.get(file);
 
         if (!document) {
-            lspClient.showErrorMessage('Inlay Hints request failed. File not opened in the editor.');
+            lspClient.showWarningMessage('Inlay Hints request failed. File not opened in the editor.');
             return [];
         }
 
diff --git a/src/features/source-definition.ts b/src/features/source-definition.ts
index 5b492a63..3711e83e 100644
--- a/src/features/source-definition.ts
+++ b/src/features/source-definition.ts
@@ -32,26 +32,26 @@ export class SourceDefinitionCommand {
         token?: lsp.CancellationToken,
     ): Promise<lsp.Location[] | void> {
         if (tspClient.apiVersion.lt(SourceDefinitionCommand.minVersion)) {
-            lspClient.showErrorMessage('Go to Source Definition failed. Requires TypeScript 4.7+.');
+            lspClient.showWarningMessage('Go to Source Definition failed. Requires TypeScript 4.7+.');
             return;
         }
 
         if (!position || typeof position.character !== 'number' || typeof position.line !== 'number') {
-            lspClient.showErrorMessage('Go to Source Definition failed. Invalid position.');
+            lspClient.showWarningMessage('Go to Source Definition failed. Invalid position.');
             return;
         }
 
         let file: string | undefined;
 
         if (!uri || typeof uri !== 'string' || !(file = uriToPath(uri))) {
-            lspClient.showErrorMessage('Go to Source Definition failed. No resource provided.');
+            lspClient.showWarningMessage('Go to Source Definition failed. No resource provided.');
             return;
         }
 
         const document = documents.get(file);
 
         if (!document) {
-            lspClient.showErrorMessage('Go to Source Definition failed. File not opened in the editor.');
+            lspClient.showWarningMessage('Go to Source Definition failed. File not opened in the editor.');
             return;
         }
 
@@ -62,7 +62,7 @@ export class SourceDefinitionCommand {
         }, async () => {
             const response = await tspClient.request(CommandTypes.FindSourceDefinition, args, token);
             if (response.type !== 'response' || !response.body) {
-                lspClient.showErrorMessage('No source definitions found.');
+                lspClient.showWarningMessage('No source definitions found.');
                 return;
             }
             return response.body.map(reference => toLocation(reference, documents));
diff --git a/src/lsp-client.ts b/src/lsp-client.ts
index bf154a7f..ea2f9076 100644
--- a/src/lsp-client.ts
+++ b/src/lsp-client.ts
@@ -19,7 +19,7 @@ export interface LspClient {
     createProgressReporter(token?: lsp.CancellationToken, workDoneProgress?: lsp.WorkDoneProgressReporter): Promise<lsp.WorkDoneProgressReporter>;
     withProgress<R>(options: WithProgressOptions, task: (progress: lsp.WorkDoneProgressReporter) => Promise<R>): Promise<R>;
     publishDiagnostics(args: lsp.PublishDiagnosticsParams): void;
-    showErrorMessage(message: string): void;
+    showWarningMessage(message: string): void;
     logMessage(args: lsp.LogMessageParams): void;
     applyWorkspaceEdit(args: lsp.ApplyWorkspaceEditParams): Promise<lsp.ApplyWorkspaceEditResult>;
     rename(args: lsp.TextDocumentPositionParams): Promise<any>;
@@ -55,8 +55,8 @@ export class LspClientImpl implements LspClient {
         this.connection.sendDiagnostics(params);
     }
 
-    showErrorMessage(message: string): void {
-        this.connection.sendNotification(lsp.ShowMessageNotification.type, { type: MessageType.Error, message });
+    showWarningMessage(message: string): void {
+        this.connection.sendRequest(lsp.ShowMessageRequest.type, { type: MessageType.Warning, message });
     }
 
     logMessage(args: lsp.LogMessageParams): void {
diff --git a/src/lsp-server.ts b/src/lsp-server.ts
index cc7c9e00..b41ab355 100644
--- a/src/lsp-server.ts
+++ b/src/lsp-server.ts
@@ -40,6 +40,8 @@ import { Position, Range } from './utils/typeConverters.js';
 import { CodeActionKind } from './utils/types.js';
 import { ConfigurationManager } from './configuration-manager.js';
 
+const LARGE_NUMBER_OF_COMPLETIONS_WARNING_TRIGGER = 10000;
+
 export class LspServer {
     private _tspClient: TspClient | null = null;
     private hasShutDown = false;
@@ -666,9 +668,36 @@ export class LspServer {
             optionalReplacementRange: optionalReplacementSpan ? Range.fromTextSpan(optionalReplacementSpan) : undefined,
         };
         const completions = asCompletionItems(entries, this.completionDataCache, file, params.position, document, this.documents, completionOptions, this.features, completionContext);
+
+        if (entries.length > LARGE_NUMBER_OF_COMPLETIONS_WARNING_TRIGGER) {
+            setImmediate(() => this.triggerLargeNumberOfCompletionsWarning(entries));
+        }
+
         return lsp.CompletionList.create(completions, isIncomplete);
     }
 
+    private triggerLargeNumberOfCompletionsWarning(entries: readonly ts.server.protocol.CompletionEntry[]): void {
+        const largeCompletionsMap = new Map<string, number>();
+        for (const entry of entries) {
+            if (!entry.source) {
+                continue;
+            }
+
+            const { source } = entry;
+            const count = largeCompletionsMap.get(source) || 0;
+            largeCompletionsMap.set(source, count + 1);
+        }
+
+        const largeCompletionsList: [string, number][] = [];
+        for (const [key, count] of largeCompletionsMap.entries()) {
+            largeCompletionsList.push([key, count]);
+        }
+
+        largeCompletionsList.sort((a, b) => b[1] - a[1]).splice(25);
+        const table = largeCompletionsList.map(([key, count]) => `  ${key}: ${count}`).join('\n');
+        this.options.lspClient.showWarningMessage(`Large number (${entries.length}) of completions received.\n\nModules contributing most completions:\nConsider ignoring the biggest offenders with the \`autoImportFileExcludePatterns\` option. ${table}`);
+    }
+
     async completionResolve(item: lsp.CompletionItem, token?: lsp.CancellationToken): Promise<lsp.CompletionItem> {
         this.logger.log('completion/resolve', item);
         item.data = item.data?.cacheId !== undefined ? this.completionDataCache.get(item.data.cacheId) : item.data;
diff --git a/src/test-utils.ts b/src/test-utils.ts
index 158850e1..9d7b9da2 100644
--- a/src/test-utils.ts
+++ b/src/test-utils.ts
@@ -143,7 +143,7 @@ export class TestLspClient implements LspClient {
         return this.options.publishDiagnostics(args);
     }
 
-    showErrorMessage(message: string): void {
+    showWarningMessage(message: string): void {
         this.logger.error(`[showErrorMessage] ${message}`);
     }