diff --git a/packages/twenty-server/src/database/commands/command-runners/workspace-iterator.service.ts b/packages/twenty-server/src/database/commands/command-runners/workspace-iterator.service.ts
index ebd92496c5..5f761d9725 100644
--- a/packages/twenty-server/src/database/commands/command-runners/workspace-iterator.service.ts
+++ b/packages/twenty-server/src/database/commands/command-runners/workspace-iterator.service.ts
@@ -90,6 +90,15 @@ export class WorkspaceIteratorService {
               ? await this.globalWorkspaceOrmManager.getGlobalWorkspaceDataSource()
               : undefined;
 
+            if (!isDefined(dataSource)) {
+              this.logger.warn(
+                `Could not retrieve a workspace data source for workspace ${workspaceId} ` +
+                  `(index ${index + 1}/${workspaceIdsToProcess.length}): ` +
+                  `workspaceRowFound=${isDefined(workspace)}, ` +
+                  `databaseSchema=${JSON.stringify(workspace?.databaseSchema ?? null)}`,
+              );
+            }
+
             await callback({
               workspaceId,
               dataSource,
diff --git a/packages/twenty-server/src/database/commands/upgrade-version-command/2-21/2-21-instance-command-slow-1783934147089-backfill-workspace-database-schema.ts b/packages/twenty-server/src/database/commands/upgrade-version-command/2-21/2-21-instance-command-slow-1783934147089-backfill-workspace-database-schema.ts
new file mode 100644
index 0000000000..9ae3ccab99
--- /dev/null
+++ b/packages/twenty-server/src/database/commands/upgrade-version-command/2-21/2-21-instance-command-slow-1783934147089-backfill-workspace-database-schema.ts
@@ -0,0 +1,55 @@
+import { DataSource, QueryRunner } from 'typeorm';
+
+import { RegisteredInstanceCommand } from 'src/engine/core-modules/upgrade/decorators/registered-instance-command.decorator';
+import { SlowInstanceCommand } from 'src/engine/core-modules/upgrade/interfaces/slow-instance-command.interface';
+import { getWorkspaceSchemaName } from 'src/engine/workspace-datasource/utils/get-workspace-schema-name.util';
+
+@RegisteredInstanceCommand('2.21.0', 1783934147089, { type: 'slow' })
+export class BackfillWorkspaceDatabaseSchemaSlowInstanceCommand
+  implements SlowInstanceCommand
+{
+  // Schema names are deterministic from the workspace id, so we backfill them
+  // unconditionally — even if the schema doesn't exist yet in Postgres — which
+  // lets up() add the check constraint fully validated.
+  async runDataMigration(dataSource: DataSource): Promise<void> {
+    const workspacesWithoutSchema: { id: string }[] = await dataSource.query(
+      `SELECT id FROM "core"."workspace"
+       WHERE ("databaseSchema" IS NULL OR "databaseSchema" = '')
+         AND "activationStatus" NOT IN ('PENDING_CREATION', 'ONGOING_CREATION')`,
+    );
+
+    if (workspacesWithoutSchema.length === 0) {
+      return;
+    }
+
+    await dataSource.query(
+      `UPDATE "core"."workspace" AS w
+       SET "databaseSchema" = data.schema_name
+       FROM (
+         SELECT UNNEST($1::uuid[]) AS id, UNNEST($2::text[]) AS schema_name
+       ) AS data
+       WHERE w.id = data.id`,
+      [
+        workspacesWithoutSchema.map((workspace) => workspace.id),
+        workspacesWithoutSchema.map((workspace) =>
+          getWorkspaceSchemaName(workspace.id),
+        ),
+      ],
+    );
+  }
+
+  public async up(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `ALTER TABLE "core"."workspace" DROP CONSTRAINT IF EXISTS "workspace_requires_database_schema"`,
+    );
+    await queryRunner.query(
+      `ALTER TABLE "core"."workspace" ADD CONSTRAINT "workspace_requires_database_schema" CHECK ("activationStatus" IN ('PENDING_CREATION', 'ONGOING_CREATION') OR ("databaseSchema" IS NOT NULL AND "databaseSchema" <> ''))`,
+    );
+  }
+
+  public async down(queryRunner: QueryRunner): Promise<void> {
+    await queryRunner.query(
+      `ALTER TABLE "core"."workspace" DROP CONSTRAINT IF EXISTS "workspace_requires_database_schema"`,
+    );
+  }
+}
diff --git a/packages/twenty-server/src/database/commands/upgrade-version-command/instance-commands.constant.ts b/packages/twenty-server/src/database/commands/upgrade-version-command/instance-commands.constant.ts
index b17594410d..c219c8da66 100644
--- a/packages/twenty-server/src/database/commands/upgrade-version-command/instance-commands.constant.ts
+++ b/packages/twenty-server/src/database/commands/upgrade-version-command/instance-commands.constant.ts
@@ -108,6 +108,7 @@ import { CreateWorkflowCoreTableFastInstanceCommand } from './2-20/2-20-instance
 import { AddGalleryImagesToApplicationRegistrationFastInstanceCommand } from './2-20/2-20-instance-command-fast-1783615890055-add-gallery-images-to-application-registration';
 import { BackfillGalleryImagesOnApplicationRegistrationSlowInstanceCommand } from './2-20/2-20-instance-command-slow-1783615890056-backfill-gallery-images-on-application-registration';
 import { AddWorkflowVersionSyncableColumnsFastInstanceCommand } from './2-20/2-20-instance-command-fast-1783603454480-add-workflow-version-syncable-columns';
+import { BackfillWorkspaceDatabaseSchemaSlowInstanceCommand } from './2-21/2-21-instance-command-slow-1783934147089-backfill-workspace-database-schema';
 
 export const INSTANCE_COMMANDS = [
   AddViewFieldGroupIdIndexOnViewFieldFastInstanceCommand,
@@ -218,4 +219,5 @@ export const INSTANCE_COMMANDS = [
   AddGalleryImagesToApplicationRegistrationFastInstanceCommand,
   BackfillGalleryImagesOnApplicationRegistrationSlowInstanceCommand,
   AddWorkflowVersionSyncableColumnsFastInstanceCommand,
+  BackfillWorkspaceDatabaseSchemaSlowInstanceCommand,
 ];
diff --git a/packages/twenty-server/src/engine/core-modules/workspace/workspace.entity.ts b/packages/twenty-server/src/engine/core-modules/workspace/workspace.entity.ts
index 8c2a42bd59..141e09abb8 100644
--- a/packages/twenty-server/src/engine/core-modules/workspace/workspace.entity.ts
+++ b/packages/twenty-server/src/engine/core-modules/workspace/workspace.entity.ts
@@ -67,6 +67,10 @@ registerEnumType(WorkspaceDiscoverability, {
   'onboarded_workspace_requires_default_role',
   `"activationStatus" IN ('PENDING_CREATION', 'ONGOING_CREATION') OR "defaultRoleId" IS NOT NULL`,
 )
+@Check(
+  'workspace_requires_database_schema',
+  `"activationStatus" IN ('PENDING_CREATION', 'ONGOING_CREATION') OR ("databaseSchema" IS NOT NULL AND "databaseSchema" <> '')`,
+)
 @Entity({ name: 'workspace', schema: 'core' })
 @ObjectType('Workspace')
 export class WorkspaceEntity {
diff --git a/packages/twenty-server/src/engine/workspace-datasource/workspace-datasource.service.ts b/packages/twenty-server/src/engine/workspace-datasource/workspace-datasource.service.ts
index 3cd4cafd84..7411b4bb78 100644
--- a/packages/twenty-server/src/engine/workspace-datasource/workspace-datasource.service.ts
+++ b/packages/twenty-server/src/engine/workspace-datasource/workspace-datasource.service.ts
@@ -37,7 +37,7 @@ export class WorkspaceDataSourceService {
     }
   }
 
-  public async checkSchemaExists(workspaceId: string) {
+  public async checkSchemaExists(workspaceId: string): Promise<boolean> {
     const workspace = await this.workspaceRepository.findOne({
       select: ['databaseSchema'],
       where: { id: workspaceId },