diff --git a/packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/jobs/__tests__/stream-agent-chat.job.spec.ts b/packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/jobs/__tests__/stream-agent-chat.job.spec.ts
index 44b38bdfb7..c2cb7d5751 100644
--- a/packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/jobs/__tests__/stream-agent-chat.job.spec.ts
+++ b/packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/jobs/__tests__/stream-agent-chat.job.spec.ts
@@ -3,6 +3,8 @@ import { type UIMessageChunk } from 'ai';
 import { type WorkspaceEntity } from 'src/engine/core-modules/workspace/workspace.entity';
 import { StreamAgentChatJob } from 'src/engine/metadata-modules/ai/ai-chat/jobs/stream-agent-chat.job';
 import { type StreamAgentChatJobData } from 'src/engine/metadata-modules/ai/ai-chat/jobs/stream-agent-chat-job.types';
+import { AiExceptionCode } from 'src/engine/metadata-modules/ai/ai.exception';
+
 
 type PublishedEvent = { type: string } & Record<string, unknown>;
 
@@ -294,6 +296,36 @@ describe('StreamAgentChatJob', () => {
     );
   });
 
+  it('persists the error and unblocks the thread when the workspace is missing', async () => {
+    const { job, publishedEvents, threadRepository } = buildJob({
+      workspaceFound: false,
+    });
+
+    await expect(job.handle(jobData)).rejects.toMatchObject({
+      code: AiExceptionCode.WORKSPACE_NOT_FOUND,
+    });
+
+    expect(publishedEvents[publishedEvents.length - 1]).toMatchObject({
+      type: 'stream-error',
+      code: AiExceptionCode.WORKSPACE_NOT_FOUND,
+    });
+    expect(threadRepository.update).toHaveBeenCalledWith(
+      'workspace-id',
+      { id: 'thread-id' },
+      {
+        lastStreamError: expect.objectContaining({
+          code: AiExceptionCode.WORKSPACE_NOT_FOUND,
+        }),
+      },
+    );
+    expect(threadRepository.update).toHaveBeenCalledWith(
+      'workspace-id',
+      { id: 'thread-id', activeStreamId: 'stream-id' },
+      { activeStreamId: null },
+    );
+  });
+
+
   it('resolves without flushing the queue when the stream is cancelled', async () => {
     let triggerCancel: (() => void) | undefined;
 
diff --git a/packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/jobs/stream-agent-chat.job.ts b/packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/jobs/stream-agent-chat.job.ts
index 3045a32ecc..2bf046325b 100644
--- a/packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/jobs/stream-agent-chat.job.ts
+++ b/packages/twenty-server/src/engine/metadata-modules/ai/ai-chat/jobs/stream-agent-chat.job.ts
@@ -21,6 +21,10 @@ import { AgentMessageRole } from 'src/engine/metadata-modules/ai/ai-agent-execut
 import { computeCostBreakdown } from 'src/engine/metadata-modules/ai/ai-billing/utils/compute-cost-breakdown.util';
 import { convertDollarsToBillingCredits } from 'src/engine/metadata-modules/ai/ai-billing/utils/convert-dollars-to-billing-credits.util';
 import { extractCacheCreationTokens } from 'src/engine/metadata-modules/ai/ai-billing/utils/extract-cache-creation-tokens.util';
+import {
+  AiException,
+  AiExceptionCode,
+} from 'src/engine/metadata-modules/ai/ai.exception';
 import { AgentChatThreadEntity } from 'src/engine/metadata-modules/ai/ai-chat/entities/agent-chat-thread.entity';
 import { AgentChatCancelSubscriberService } from 'src/engine/metadata-modules/ai/ai-chat/services/agent-chat-cancel-subscriber.service';
 import { AgentChatEventPublisherService } from 'src/engine/metadata-modules/ai/ai-chat/services/agent-chat-event-publisher.service';
@@ -64,25 +68,6 @@ export class StreamAgentChatJob {
   async handle(data: StreamAgentChatJobData): Promise<void> {
     await this.eventPublisherService.resetStreamState(data.threadId);
 
-    const workspace = await this.workspaceRepository.findOne({
-      where: { id: data.workspaceId },
-    });
-
-    if (!workspace) {
-      this.logger.error(`Workspace ${data.workspaceId} not found`);
-      await this.eventPublisherService.publish({
-        threadId: data.threadId,
-        workspaceId: data.workspaceId,
-        event: {
-          type: 'stream-error',
-          code: 'WORKSPACE_NOT_FOUND',
-          message: `Workspace ${data.workspaceId} not found`,
-        },
-      });
-
-      return;
-    }
-
     const abortController = new AbortController();
     const cancelChannel = getCancelChannel(data.threadId);
 
@@ -91,6 +76,17 @@ export class StreamAgentChatJob {
     });
 
     try {
+      const workspace = await this.workspaceRepository.findOne({
+        where: { id: data.workspaceId },
+      });
+
+      if (!workspace) {
+        throw new AiException(
+          `Workspace ${data.workspaceId} not found`,
+          AiExceptionCode.WORKSPACE_NOT_FOUND,
+        );
+      }
+
       await this.executeStream(data, workspace, abortController.signal);
     } catch (error) {
       this.logger.error(
diff --git a/packages/twenty-server/src/engine/metadata-modules/ai/ai.exception.ts b/packages/twenty-server/src/engine/metadata-modules/ai/ai.exception.ts
index cd4431d4b9..919d8e7650 100644
--- a/packages/twenty-server/src/engine/metadata-modules/ai/ai.exception.ts
+++ b/packages/twenty-server/src/engine/metadata-modules/ai/ai.exception.ts
@@ -11,6 +11,7 @@ export enum AiExceptionCode {
   AGENT_EXECUTION_FAILED = 'AGENT_EXECUTION_FAILED',
   INVALID_AGENT_INPUT = 'INVALID_AGENT_INPUT',
   THREAD_NOT_FOUND = 'THREAD_NOT_FOUND',
+  WORKSPACE_NOT_FOUND = 'WORKSPACE_NOT_FOUND',
   INVALID_CHAT_THREAD_TITLE = 'INVALID_CHAT_THREAD_TITLE',
   MESSAGE_NOT_FOUND = 'MESSAGE_NOT_FOUND',
   QUESTION_NOT_PENDING = 'QUESTION_NOT_PENDING',
@@ -36,6 +37,8 @@ const getAiExceptionUserFriendlyMessage = (code: AiExceptionCode) => {
       return msg`Invalid agent input.`;
     case AiExceptionCode.THREAD_NOT_FOUND:
       return msg`Chat thread not found.`;
+    case AiExceptionCode.WORKSPACE_NOT_FOUND:
+      return msg`Workspace not found.`;
     case AiExceptionCode.INVALID_CHAT_THREAD_TITLE:
       return msg`Chat thread title cannot be empty.`;
     case AiExceptionCode.MESSAGE_NOT_FOUND:
diff --git a/packages/twenty-server/src/engine/metadata-modules/ai/utils/ai-graphql-api-exception-handler.util.ts b/packages/twenty-server/src/engine/metadata-modules/ai/utils/ai-graphql-api-exception-handler.util.ts
index 1286dc3809..5b394de6c1 100644
--- a/packages/twenty-server/src/engine/metadata-modules/ai/utils/ai-graphql-api-exception-handler.util.ts
+++ b/packages/twenty-server/src/engine/metadata-modules/ai/utils/ai-graphql-api-exception-handler.util.ts
@@ -23,6 +23,7 @@ export const aiGraphqlApiExceptionHandler = (error: Error) => {
     switch (error.code) {
       case AiExceptionCode.AGENT_NOT_FOUND:
       case AiExceptionCode.THREAD_NOT_FOUND:
+      case AiExceptionCode.WORKSPACE_NOT_FOUND:
       case AiExceptionCode.MESSAGE_NOT_FOUND:
       case AiExceptionCode.ROLE_NOT_FOUND:
         throw new NotFoundError(error);