diff --git a/src/Controller/Organizations/TicketsController.php b/src/Controller/Organizations/TicketsController.php
index f9b2f2bb..03ca91ff 100644
--- a/src/Controller/Organizations/TicketsController.php
+++ b/src/Controller/Organizations/TicketsController.php
@@ -22,6 +22,7 @@
 use App\Service\ActorsLister;
 use App\TicketActivity\MessageEvent;
 use App\TicketActivity\TicketEvent;
+use App\Utils\ArrayHelper;
 use App\Utils\ConstraintErrorsFormatter;
 use App\Utils\Pagination;
 use App\Utils\Time;
@@ -228,7 +229,10 @@ public function create(
             ]);
         }
 
-        $requester = $userRepository->findOneBy(['uid' => $requesterUid]);
+        $requester = ArrayHelper::find($allUsers, function ($user) use ($requesterUid): bool {
+            return $user->getUid() === $requesterUid;
+        });
+
         if (!$requester) {
             return $this->renderBadRequest('organizations/tickets/new.html.twig', [
                 'organization' => $organization,
@@ -249,29 +253,11 @@ public function create(
             ]);
         }
 
+        $assignee = null;
         if ($assigneeUid) {
-            $assignee = $userRepository->findOneBy(['uid' => $assigneeUid]);
-            if (!$assignee) {
-                return $this->renderBadRequest('organizations/tickets/new.html.twig', [
-                    'organization' => $organization,
-                    'title' => $title,
-                    'message' => $messageContent,
-                    'type' => $type,
-                    'requesterUid' => $requesterUid,
-                    'assigneeUid' => $assigneeUid,
-                    'isResolved' => $isResolved,
-                    'urgency' => $urgency,
-                    'impact' => $impact,
-                    'priority' => $priority,
-                    'allUsers' => $allUsers,
-                    'agents' => $agents,
-                    'errors' => [
-                        'assignee' => $translator->trans('ticket.assignee.invalid', [], 'errors'),
-                    ],
-                ]);
-            }
-        } else {
-            $assignee = null;
+            $assignee = ArrayHelper::find($agents, function ($agent) use ($assigneeUid): bool {
+                return $agent->getUid() === $assigneeUid;
+            });
         }
 
         $ticket = new Ticket();
diff --git a/src/Controller/Tickets/ActorsController.php b/src/Controller/Tickets/ActorsController.php
index f5f99d3d..05070885 100644
--- a/src/Controller/Tickets/ActorsController.php
+++ b/src/Controller/Tickets/ActorsController.php
@@ -12,6 +12,7 @@
 use App\Repository\UserRepository;
 use App\Service\ActorsLister;
 use App\TicketActivity\TicketEvent;
+use App\Utils\ArrayHelper;
 use Symfony\Component\EventDispatcher\EventDispatcherInterface;
 use Symfony\Component\HttpFoundation\Response;
 use Symfony\Component\HttpFoundation\Request;
@@ -95,7 +96,10 @@ public function update(
             ]);
         }
 
-        $requester = $userRepository->findOneBy(['uid' => $requesterUid]);
+        $requester = ArrayHelper::find($allUsers, function ($user) use ($requesterUid): bool {
+            return $user->getUid() === $requesterUid;
+        });
+
         if (!$requester) {
             return $this->renderBadRequest('tickets/actors/edit.html.twig', [
                 'ticket' => $ticket,
@@ -109,22 +113,11 @@ public function update(
             ]);
         }
 
+        $assignee = null;
         if ($assigneeUid) {
-            $assignee = $userRepository->findOneBy(['uid' => $assigneeUid]);
-            if (!$assignee) {
-                return $this->renderBadRequest('tickets/actors/edit.html.twig', [
-                    'ticket' => $ticket,
-                    'requesterUid' => $requesterUid,
-                    'assigneeUid' => $assigneeUid,
-                    'allUsers' => $allUsers,
-                    'agents' => $agents,
-                    'errors' => [
-                        'assignee' => $translator->trans('ticket.assignee.invalid', [], 'errors'),
-                    ],
-                ]);
-            }
-        } else {
-            $assignee = null;
+            $assignee = ArrayHelper::find($agents, function ($agent) use ($assigneeUid): bool {
+                return $agent->getUid() === $assigneeUid;
+            });
         }
 
         $previousAssignee = $ticket->getAssignee();
diff --git a/tests/AuthorizationHelper.php b/tests/AuthorizationHelper.php
index 6a2eaa81..19a4b7ca 100644
--- a/tests/AuthorizationHelper.php
+++ b/tests/AuthorizationHelper.php
@@ -55,9 +55,14 @@ public function grantAdmin(User $user, array $permissions): void
 
     /**
      * @param string[] $permissions
+     * @param 'user'|'agent' $type
      */
-    public function grantOrga(User $user, array $permissions, ?Organization $organization = null): void
-    {
+    public function grantOrga(
+        User $user,
+        array $permissions,
+        ?Organization $organization = null,
+        string $type = 'agent',
+    ): void {
         if (empty($permissions)) {
             return;
         }
@@ -72,12 +77,12 @@ public function grantOrga(User $user, array $permissions, ?Organization $organiz
         /** @var \App\Repository\AuthorizationRepository $authorizationRepo */
         $authorizationRepo = $entityManager->getRepository(Authorization::class);
 
-        $permissions = Role::sanitizePermissions('agent', $permissions);
+        $permissions = Role::sanitizePermissions($type, $permissions);
 
         $role = new Role();
         $role->setName(Random::hex(10));
         $role->setDescription('The role description');
-        $role->setType('agent');
+        $role->setType($type);
         $role->setPermissions($permissions);
 
         $roleRepo->save($role);
diff --git a/tests/Controller/Organizations/TicketsControllerTest.php b/tests/Controller/Organizations/TicketsControllerTest.php
index 818e430c..cfe72420 100644
--- a/tests/Controller/Organizations/TicketsControllerTest.php
+++ b/tests/Controller/Organizations/TicketsControllerTest.php
@@ -195,7 +195,7 @@ public function testPostCreateCreatesATicketAndRedirects(): void
         list(
             $user,
             $requester,
-        ) = UserFactory::createMany(3);
+        ) = UserFactory::createMany(2);
         $client->loginUser($user->object());
         $organization = OrganizationFactory::createOne();
         $this->grantOrga($user->object(), [
@@ -205,6 +205,9 @@ public function testPostCreateCreatesATicketAndRedirects(): void
             'orga:update:tickets:actors',
             'orga:update:tickets:priority',
         ], $organization->object());
+        $this->grantOrga($requester->object(), [
+            'orga:create:tickets',
+        ], $organization->object());
         $title = 'My ticket';
         $messageContent = 'My message';
 
@@ -351,15 +354,14 @@ public function testPostCreateAttachesDocumentsToMessage(): void
         $this->assertSame($message->getUid(), $messageDocument2->getMessage()->getUid());
     }
 
-    public function testPostCreateCanAssignsAUser(): void
+    public function testPostCreateCanAssignAUser(): void
     {
         $now = new \DateTimeImmutable('2022-11-02');
         $client = static::createClient();
         list(
             $user,
-            $requester,
             $assignee
-        ) = UserFactory::createMany(3);
+        ) = UserFactory::createMany(2);
         $client->loginUser($user->object());
         $organization = OrganizationFactory::createOne();
         $this->grantOrga($user->object(), [
@@ -369,6 +371,9 @@ public function testPostCreateCanAssignsAUser(): void
             'orga:update:tickets:actors',
             'orga:update:tickets:priority',
         ], $organization->object());
+        $this->grantOrga($assignee->object(), [
+            'orga:create:tickets',
+        ], $organization->object());
         $title = 'My ticket';
         $messageContent = 'My message';
 
@@ -378,7 +383,7 @@ public function testPostCreateCanAssignsAUser(): void
         $client->request('POST', "/organizations/{$organization->getUid()}/tickets/new", [
             '_csrf_token' => $this->generateCsrfToken($client, 'create organization ticket'),
             'title' => $title,
-            'requesterUid' => $requester->getUid(),
+            'requesterUid' => $user->getUid(),
             'assigneeUid' => $assignee->getUid(),
             'type' => 'incident',
             'urgency' => 'high',
@@ -399,10 +404,7 @@ public function testPostCreateCanAssignsAUser(): void
     public function testPostCreateCanMarkATicketAsResolved(): void
     {
         $client = static::createClient();
-        list(
-            $user,
-            $requester
-        ) = UserFactory::createMany(2);
+        $user = UserFactory::createOne();
         $client->loginUser($user->object());
         $organization = OrganizationFactory::createOne();
         $this->grantOrga($user->object(), [
@@ -418,7 +420,7 @@ public function testPostCreateCanMarkATicketAsResolved(): void
         $client->request('POST', "/organizations/{$organization->getUid()}/tickets/new", [
             '_csrf_token' => $this->generateCsrfToken($client, 'create organization ticket'),
             'title' => $title,
-            'requesterUid' => $requester->getUid(),
+            'requesterUid' => $user->getUid(),
             'message' => $messageContent,
             'isResolved' => true,
         ]);
@@ -472,12 +474,14 @@ public function testPostCreateCanCreateATicketWithMinimalPermissions(): void
         $this->assertSame('webapp', $message->getVia());
     }
 
-    public function testPostCreateFailsIfTitleIsEmpty(): void
+    public function testPostCreateDoesNotAssignIfUserIsNotAgent(): void
     {
         $now = new \DateTimeImmutable('2022-11-02');
-        Time::freeze($now);
         $client = static::createClient();
-        $user = UserFactory::createOne();
+        list(
+            $user,
+            $assignee
+        ) = UserFactory::createMany(2);
         $client->loginUser($user->object());
         $organization = OrganizationFactory::createOne();
         $this->grantOrga($user->object(), [
@@ -487,25 +491,66 @@ public function testPostCreateFailsIfTitleIsEmpty(): void
             'orga:update:tickets:actors',
             'orga:update:tickets:priority',
         ], $organization->object());
-        $title = '';
+        $this->grantOrga($assignee->object(), [
+            'orga:create:tickets',
+        ], $organization->object(), 'user');
+        $title = 'My ticket';
         $messageContent = 'My message';
 
-        $this->assertSame(0, TicketFactory::count());
-
         $client->request('POST', "/organizations/{$organization->getUid()}/tickets/new", [
             '_csrf_token' => $this->generateCsrfToken($client, 'create organization ticket'),
             'title' => $title,
             'requesterUid' => $user->getUid(),
+            'assigneeUid' => $assignee->getUid(),
+            'type' => 'incident',
+            'urgency' => 'high',
+            'impact' => 'high',
+            'priority' => 'high',
+            'message' => $messageContent,
+        ]);
+
+        $this->assertSame(1, TicketFactory::count());
+        $this->assertSame(1, MessageFactory::count());
+
+        $ticket = TicketFactory::first();
+        $this->assertResponseRedirects("/tickets/{$ticket->getUid()}", 302);
+        $this->assertSame('new', $ticket->getStatus());
+        $this->assertNull($ticket->getAssignee());
+    }
+
+    public function testPostCreateFailsIfRequesterIsNotInOrganization(): void
+    {
+        $now = new \DateTimeImmutable('2022-11-02');
+        $client = static::createClient();
+        list(
+            $user,
+            $requester,
+        ) = UserFactory::createMany(2);
+        $client->loginUser($user->object());
+        $organization = OrganizationFactory::createOne();
+        $this->grantOrga($user->object(), [
+            'orga:create:tickets',
+            'orga:update:tickets:status',
+            'orga:update:tickets:type',
+            'orga:update:tickets:actors',
+            'orga:update:tickets:priority',
+        ], $organization->object());
+        $title = 'My ticket';
+        $messageContent = 'My message';
+
+        $client->request('POST', "/organizations/{$organization->getUid()}/tickets/new", [
+            '_csrf_token' => $this->generateCsrfToken($client, 'create organization ticket'),
+            'title' => $title,
+            'requesterUid' => $requester->getUid(),
             'message' => $messageContent,
         ]);
 
-        Time::unfreeze();
         $this->assertSame(0, TicketFactory::count());
         $this->assertSame(0, MessageFactory::count());
-        $this->assertSelectorTextContains('#title-error', 'Enter a title');
+        $this->assertSelectorTextContains('#requester-error', 'Select a user from the list');
     }
 
-    public function testPostCreateFailsIfTitleIsTooLong(): void
+    public function testPostCreateFailsIfTitleIsEmpty(): void
     {
         $now = new \DateTimeImmutable('2022-11-02');
         Time::freeze($now);
@@ -520,7 +565,7 @@ public function testPostCreateFailsIfTitleIsTooLong(): void
             'orga:update:tickets:actors',
             'orga:update:tickets:priority',
         ], $organization->object());
-        $title = str_repeat('a', 256);
+        $title = '';
         $messageContent = 'My message';
 
         $this->assertSame(0, TicketFactory::count());
@@ -535,10 +580,10 @@ public function testPostCreateFailsIfTitleIsTooLong(): void
         Time::unfreeze();
         $this->assertSame(0, TicketFactory::count());
         $this->assertSame(0, MessageFactory::count());
-        $this->assertSelectorTextContains('#title-error', 'Enter a title of less than 255 characters');
+        $this->assertSelectorTextContains('#title-error', 'Enter a title');
     }
 
-    public function testPostCreateFailsIfMessageIsEmpty(): void
+    public function testPostCreateFailsIfTitleIsTooLong(): void
     {
         $now = new \DateTimeImmutable('2022-11-02');
         Time::freeze($now);
@@ -553,8 +598,8 @@ public function testPostCreateFailsIfMessageIsEmpty(): void
             'orga:update:tickets:actors',
             'orga:update:tickets:priority',
         ], $organization->object());
-        $title = 'My ticket';
-        $messageContent = '';
+        $title = str_repeat('a', 256);
+        $messageContent = 'My message';
 
         $this->assertSame(0, TicketFactory::count());
 
@@ -568,10 +613,10 @@ public function testPostCreateFailsIfMessageIsEmpty(): void
         Time::unfreeze();
         $this->assertSame(0, TicketFactory::count());
         $this->assertSame(0, MessageFactory::count());
-        $this->assertSelectorTextContains('#message-error', 'Enter a message');
+        $this->assertSelectorTextContains('#title-error', 'Enter a title of less than 255 characters');
     }
 
-    public function testPostCreateFailsIfRequesterIsInvalid(): void
+    public function testPostCreateFailsIfMessageIsEmpty(): void
     {
         $now = new \DateTimeImmutable('2022-11-02');
         Time::freeze($now);
@@ -587,24 +632,24 @@ public function testPostCreateFailsIfRequesterIsInvalid(): void
             'orga:update:tickets:priority',
         ], $organization->object());
         $title = 'My ticket';
-        $messageContent = 'My message';
+        $messageContent = '';
 
         $this->assertSame(0, TicketFactory::count());
 
         $client->request('POST', "/organizations/{$organization->getUid()}/tickets/new", [
             '_csrf_token' => $this->generateCsrfToken($client, 'create organization ticket'),
             'title' => $title,
-            'requesterUid' => 'not an uid',
+            'requesterUid' => $user->getUid(),
             'message' => $messageContent,
         ]);
 
         Time::unfreeze();
         $this->assertSame(0, TicketFactory::count());
         $this->assertSame(0, MessageFactory::count());
-        $this->assertSelectorTextContains('#requester-error', 'Select a user from the list');
+        $this->assertSelectorTextContains('#message-error', 'Enter a message');
     }
 
-    public function testPostCreateFailsIfAssigneeIsInvalid(): void
+    public function testPostCreateFailsIfRequesterIsInvalid(): void
     {
         $now = new \DateTimeImmutable('2022-11-02');
         Time::freeze($now);
@@ -627,15 +672,14 @@ public function testPostCreateFailsIfAssigneeIsInvalid(): void
         $client->request('POST', "/organizations/{$organization->getUid()}/tickets/new", [
             '_csrf_token' => $this->generateCsrfToken($client, 'create organization ticket'),
             'title' => $title,
-            'requesterUid' => $user->getUid(),
-            'assigneeUid' => 'not an uid',
+            'requesterUid' => 'not an uid',
             'message' => $messageContent,
         ]);
 
         Time::unfreeze();
         $this->assertSame(0, TicketFactory::count());
         $this->assertSame(0, MessageFactory::count());
-        $this->assertSelectorTextContains('#assignee-error', 'Select a user from the list');
+        $this->assertSelectorTextContains('#requester-error', 'Select a user from the list');
     }
 
     public function testPostCreateFailsIfCsrfTokenIsInvalid(): void
diff --git a/tests/Controller/Tickets/ActorsControllerTest.php b/tests/Controller/Tickets/ActorsControllerTest.php
index f237d78b..68d7a817 100644
--- a/tests/Controller/Tickets/ActorsControllerTest.php
+++ b/tests/Controller/Tickets/ActorsControllerTest.php
@@ -96,6 +96,8 @@ public function testPostUpdateSavesTicketAndRedirects(): void
         ) = UserFactory::createMany(3);
         $client->loginUser($user->object());
         $this->grantOrga($user->object(), ['orga:update:tickets:actors']);
+        $this->grantOrga($requester->object(), ['orga:create:tickets']);
+        $this->grantOrga($assignee->object(), ['orga:create:tickets']);
         $ticket = TicketFactory::createOne([
             'createdBy' => $user,
             'requester' => null,
@@ -120,10 +122,10 @@ public function testPostUpdateAcceptsEmptyAssignee(): void
         list(
             $user,
             $requester,
-            $assignee,
-        ) = UserFactory::createMany(3);
+        ) = UserFactory::createMany(2);
         $client->loginUser($user->object());
         $this->grantOrga($user->object(), ['orga:update:tickets:actors']);
+        $this->grantOrga($requester->object(), ['orga:create:tickets']);
         $ticket = TicketFactory::createOne([
             'createdBy' => $user,
             'requester' => null,
@@ -142,34 +144,43 @@ public function testPostUpdateAcceptsEmptyAssignee(): void
         $this->assertNull($ticket->getAssignee());
     }
 
-    public function testPostUpdateFailsIfRequesterIsInvalid(): void
+    public function testPostUpdateSetsNullIfAssigneeIsNotAgent(): void
     {
         $client = static::createClient();
-        $user = UserFactory::createOne();
+        list(
+            $user,
+            $requester,
+            $assignee,
+        ) = UserFactory::createMany(3);
         $client->loginUser($user->object());
         $this->grantOrga($user->object(), ['orga:update:tickets:actors']);
+        $this->grantOrga($requester->object(), ['orga:create:tickets']);
+        $this->grantOrga($assignee->object(), ['orga:create:tickets'], type: 'user');
         $ticket = TicketFactory::createOne([
             'createdBy' => $user,
             'requester' => null,
-            'assignee' => null,
+            'assignee' => $user,
         ]);
 
         $client->request('POST', "/tickets/{$ticket->getUid()}/actors/edit", [
             '_csrf_token' => $this->generateCsrfToken($client, 'update ticket actors'),
-            'requesterUid' => 'not an uid',
-            'assigneeUid' => $user->getUid(),
+            'requesterUid' => $requester->getUid(),
+            'assigneeUid' => $assignee->getUid(),
         ]);
 
-        $this->assertSelectorTextContains('#requester-error', 'Select a user from the list');
+        $this->assertResponseRedirects("/tickets/{$ticket->getUid()}", 302);
         $ticket->refresh();
-        $this->assertNull($ticket->getRequester());
+        $this->assertSame($requester->getUid(), $ticket->getRequester()->getUid());
         $this->assertNull($ticket->getAssignee());
     }
 
-    public function testPostUpdateFailsIfAssigneeIsInvalid(): void
+    public function testPostUpdateFailsIfRequesterIsNotInOrganization(): void
     {
         $client = static::createClient();
-        $user = UserFactory::createOne();
+        list(
+            $user,
+            $requester,
+        ) = UserFactory::createMany(2);
         $client->loginUser($user->object());
         $this->grantOrga($user->object(), ['orga:update:tickets:actors']);
         $ticket = TicketFactory::createOne([
@@ -180,11 +191,11 @@ public function testPostUpdateFailsIfAssigneeIsInvalid(): void
 
         $client->request('POST', "/tickets/{$ticket->getUid()}/actors/edit", [
             '_csrf_token' => $this->generateCsrfToken($client, 'update ticket actors'),
-            'requesterUid' => $user->getUid(),
-            'assigneeUid' => 'not an uid',
+            'requesterUid' => $requester->getUid(),
+            'assigneeUid' => $user->getUid(),
         ]);
 
-        $this->assertSelectorTextContains('#assignee-error', 'Select a user from the list');
+        $this->assertSelectorTextContains('#requester-error', 'Select a user from the list');
         $ticket->refresh();
         $this->assertNull($ticket->getRequester());
         $this->assertNull($ticket->getAssignee());
@@ -200,6 +211,8 @@ public function testPostUpdateFailsIfCsrfTokenIsInvalid(): void
         ) = UserFactory::createMany(3);
         $client->loginUser($user->object());
         $this->grantOrga($user->object(), ['orga:update:tickets:actors']);
+        $this->grantOrga($requester->object(), ['orga:create:tickets']);
+        $this->grantOrga($assignee->object(), ['orga:create:tickets']);
         $ticket = TicketFactory::createOne([
             'createdBy' => $user,
             'requester' => null,
@@ -229,6 +242,8 @@ public function testPostUpdateFailsIfAccessIsForbidden(): void
             $assignee,
         ) = UserFactory::createMany(3);
         $client->loginUser($user->object());
+        $this->grantOrga($requester->object(), ['orga:create:tickets']);
+        $this->grantOrga($assignee->object(), ['orga:create:tickets']);
         $ticket = TicketFactory::createOne([
             'createdBy' => $user,
             'requester' => null,
@@ -255,6 +270,8 @@ public function testPostUpdateFailsIfAccessToTicketIsForbidden(): void
         ) = UserFactory::createMany(3);
         $client->loginUser($user->object());
         $this->grantOrga($user->object(), ['orga:update:tickets:actors']);
+        $this->grantOrga($requester->object(), ['orga:create:tickets']);
+        $this->grantOrga($assignee->object(), ['orga:create:tickets']);
         $ticket = TicketFactory::createOne([
             'requester' => null,
             'assignee' => null,
diff --git a/translations/errors+intl-icu.en_GB.yaml b/translations/errors+intl-icu.en_GB.yaml
index bb48cea8..f6560e4f 100644
--- a/translations/errors+intl-icu.en_GB.yaml
+++ b/translations/errors+intl-icu.en_GB.yaml
@@ -37,7 +37,6 @@ role.name.required: 'Enter a name.'
 team.name.already_used: 'Enter a different name, a team already has this name.'
 team.name.max_chars: 'Enter a name of less than {limit} characters.'
 team.name.required: 'Enter a name.'
-ticket.assignee.invalid: 'Select a user from the list.'
 ticket.impact.invalid: 'Select an impact from the list.'
 ticket.priority.invalid: 'Select a priority from the list.'
 ticket.requester.invalid: 'Select a user from the list.'
diff --git a/translations/errors+intl-icu.fr_FR.yaml b/translations/errors+intl-icu.fr_FR.yaml
index b5478176..96dd035a 100644
--- a/translations/errors+intl-icu.fr_FR.yaml
+++ b/translations/errors+intl-icu.fr_FR.yaml
@@ -37,7 +37,6 @@ role.name.required: 'Saisissez un nom.'
 team.name.already_used: 'Saisissez un nom différent, une équipe porte déjà ce même nom.'
 team.name.max_chars: 'Saisissez un nom de moins de {limit} caractères.'
 team.name.required: 'Saisissez un nom.'
-ticket.assignee.invalid: 'Sélectionnez une personne de la liste.'
 ticket.impact.invalid: 'Sélectionnez un impact de la liste.'
 ticket.priority.invalid: 'Sélectionnez une priorité de la liste.'
 ticket.requester.invalid: 'Sélectionnez une personne de la liste.'