diff --git a/app/classes/Framadate/Repositories/PollRepository.php b/app/classes/Framadate/Repositories/PollRepository.php
index 4efda19..2e3f68a 100644
--- a/app/classes/Framadate/Repositories/PollRepository.php
+++ b/app/classes/Framadate/Repositories/PollRepository.php
@@ -39,9 +39,8 @@ class PollRepository extends AbstractRepository {
      */
     public function findById($poll_id)
     {
-        $prepared = $this->prepare('SELECT * FROM ' . Utils::table('poll') . ' WHERE id = ?');
+        $prepared = $this->connect->executeQuery('SELECT * FROM ' . Utils::table('poll') . ' WHERE id = ?', [$poll_id]);
 
-        $prepared->execute([$poll_id]);
         $poll = $prepared->fetch();
         $prepared->closeCursor();
 
@@ -54,9 +53,8 @@ class PollRepository extends AbstractRepository {
      * @return mixed
      */
     public function findByAdminId($admin_poll_id) {
-        $prepared = $this->prepare('SELECT * FROM ' . Utils::table('poll') . ' WHERE admin_id = ?');
+        $prepared = $this->connect->executeQuery('SELECT * FROM ' . Utils::table('poll') . ' WHERE admin_id = ?', [$admin_poll_id]);
 
-        $prepared->execute([$admin_poll_id]);
         $poll = $prepared->fetch();
         $prepared->closeCursor();
 
@@ -124,14 +122,12 @@ class PollRepository extends AbstractRepository {
     /**
      * Find old polls. Limit: 20.
      *
-     * @param int $limit
      * @throws \Doctrine\DBAL\DBALException
      * @return array Array of old polls
      */
-    public function findOldPolls($limit = 20)
+    public function findOldPolls()
     {
-        $prepared = $this->prepare('SELECT * FROM ' . Utils::table('poll') . ' WHERE DATE_ADD(end_date, INTERVAL ? DAY) < NOW() AND end_date != 0 LIMIT ?');
-        $prepared->execute([PURGE_DELAY, $limit]);
+        $prepared = $this->connect->executeQuery('SELECT * FROM ' . Utils::table('poll') . ' WHERE DATE_ADD(end_date, INTERVAL ? DAY) < NOW() AND end_date != 0 LIMIT 20', [PURGE_DELAY]);
 
         return $prepared->fetchAll();
     }
diff --git a/app/classes/Framadate/Repositories/SlotRepository.php b/app/classes/Framadate/Repositories/SlotRepository.php
index 5139073..55cfa25 100644
--- a/app/classes/Framadate/Repositories/SlotRepository.php
+++ b/app/classes/Framadate/Repositories/SlotRepository.php
@@ -18,6 +18,7 @@
  */
 namespace Framadate\Repositories;
 
+use Framadate\Choice;
 use Framadate\Utils;
 
 class SlotRepository extends AbstractRepository {
@@ -29,6 +30,7 @@ class SlotRepository extends AbstractRepository {
      */
     public function insertSlots($poll_id, $choices) {
         foreach ($choices as $choice) {
+            /** @var Choice $choice */
             // We prepared the slots (joined by comas)
             $joinedSlots = null;
             $first = true;
@@ -42,7 +44,11 @@ class SlotRepository extends AbstractRepository {
             }
 
             // We execute the insertion
-            $this->connect->insert(Utils::table('slot'), ['poll_id' => $poll_id, 'title' => $choice->getName(), 'moments' => $joinedSlots]);
+            $this->connect->insert(Utils::table('slot'), [
+                'poll_id' => $poll_id,
+                'title' => $choice->getName(),
+                'moments' => $joinedSlots
+            ]);
         }
     }
 
diff --git a/app/classes/Framadate/Services/AdminPollService.php b/app/classes/Framadate/Services/AdminPollService.php
index 02e3c99..51760f9 100644
--- a/app/classes/Framadate/Services/AdminPollService.php
+++ b/app/classes/Framadate/Services/AdminPollService.php
@@ -2,6 +2,7 @@
 namespace Framadate\Services;
 
 use Doctrine\DBAL\Connection;
+use Doctrine\DBAL\DBALException;
 use Framadate\Exception\MomentAlreadyExistsException;
 use Framadate\Repositories\RepositoryFactory;
 
@@ -196,36 +197,46 @@ class AdminPollService {
      * @param $datetime int The datetime
      * @param $new_moment string The moment's name
      * @throws MomentAlreadyExistsException When the moment to add already exists in database
+     * @throws \Doctrine\DBAL\ConnectionException
      */
     public function addDateSlot($poll_id, $datetime, $new_moment) {
         $this->logService->log('ADD_COLUMN', 'id:' . $poll_id . ', datetime:' . $datetime . ', moment:' . $new_moment);
 
-        $slots = $this->slotRepository->listByPollId($poll_id);
-        $result = $this->findInsertPosition($slots, $datetime);
-
-        // Begin transaction
-        $this->connect->beginTransaction();
-
-        if ($result->slot !== null) {
-            $slot = $result->slot;
-            $moments = explode(',', $slot->moments);
-
-            // Check if moment already exists (maybe not necessary)
-            if (in_array($new_moment, $moments, true)) {
-                throw new MomentAlreadyExistsException();
-            }
-
-            // Update found slot
-            $moments[] = $new_moment;
-            $this->slotRepository->update($poll_id, $datetime, implode(',', $moments));
-        } else {
-            $this->slotRepository->insert($poll_id, $datetime, $new_moment);
+        try {
+            $slots = $this->slotRepository->listByPollId($poll_id);
+            $result = $this->findInsertPosition($slots, $datetime);
+        } catch (DBALException $e) {
+            $this->logService->log('ERROR', "Database error, couldn't find slot insert position" . $e->getMessage());
+            return;
         }
 
-        $this->voteRepository->insertDefault($poll_id, $result->insert);
+        try {
+            // Begin transaction
+            $this->connect->beginTransaction();
 
-        // Commit transaction
-        $this->connect->commit();
+            if ($result->slot !== null) {
+                $slot = $result->slot;
+                $moments = explode(',', $slot->moments);
+
+                // Check if moment already exists (maybe not necessary)
+                if (in_array($new_moment, $moments, true)) {
+                    throw new MomentAlreadyExistsException();
+                }
+
+                // Update found slot
+                $moments[] = $new_moment;
+                $this->slotRepository->update($poll_id, $datetime, implode(',', $moments));
+            } else {
+                $this->slotRepository->insert($poll_id, $datetime, $new_moment);
+            }
+
+            $this->voteRepository->insertDefault($poll_id, $result->insert);
+
+            // Commit transaction
+            $this->connect->commit();
+        } catch (DBALException $e) {
+            $this->connect->rollBack();
+        }
     }
 
     /**
@@ -237,6 +248,8 @@ class AdminPollService {
      * @param $poll_id int The ID of the poll
      * @param $title int The title
      * @throws MomentAlreadyExistsException When the moment to add already exists in database
+     * @throws \Doctrine\DBAL\ConnectionException
+     * @throws \Doctrine\DBAL\DBALException
      */
     public function addClassicSlot($poll_id, $title) {
         $this->logService->log('ADD_COLUMN', 'id:' . $poll_id . ', title:' . $title);
diff --git a/app/classes/Framadate/Services/PollService.php b/app/classes/Framadate/Services/PollService.php
index 10d8e49..cc10300 100644
--- a/app/classes/Framadate/Services/PollService.php
+++ b/app/classes/Framadate/Services/PollService.php
@@ -19,6 +19,7 @@
 namespace Framadate\Services;
 
 use Doctrine\DBAL\Connection;
+use Doctrine\DBAL\ConnectionException;
 use Doctrine\DBAL\DBALException;
 use Framadate\Exception\AlreadyExistsException;
 use Framadate\Exception\ConcurrentEditionException;
@@ -49,20 +50,31 @@ class PollService {
      * Find a poll from its ID.
      *
      * @param $poll_id int The ID of the poll
-     * @throws \Doctrine\DBAL\DBALException
      * @return \stdClass|null The found poll, or null
      */
     function findById($poll_id) {
-        if (preg_match(POLL_REGEX, $poll_id)) {
-            return $this->pollRepository->findById($poll_id);
+        try {
+            if (preg_match(POLL_REGEX, $poll_id)) {
+                return $this->pollRepository->findById($poll_id);
+            }
+        } catch (DBALException $e) {
+            $this->logService->log('ERROR', 'Database error : ' . $e->getMessage());
         }
 
         return null;
     }
 
+    /**
+     * @param $admin_poll_id
+     * @return mixed|null
+     */
     public function findByAdminId($admin_poll_id) {
-        if (preg_match(ADMIN_POLL_REGEX, $admin_poll_id)) {
-            return $this->pollRepository->findByAdminId($admin_poll_id);
+        try {
+            if (preg_match(ADMIN_POLL_REGEX, $admin_poll_id)) {
+                return $this->pollRepository->findByAdminId($admin_poll_id);
+            }
+        } catch (DBALException $e) {
+            $this->logService->log('ERROR', 'Database error : ' . $e->getMessage());
         }
 
         return null;
@@ -149,27 +161,36 @@ class PollService {
     function createPoll(Form $form) {
         // Generate poll IDs, loop while poll ID already exists
 
-        if (empty($form->id)) { // User want us to generate an id for him
-            do {
-                $poll_id = $this->random(16);
-            } while ($this->pollRepository->existsById($poll_id));
-            $admin_poll_id = $poll_id . $this->random(8);
-        } else { // User have choosen the poll id
-            $poll_id = $form->id;
-            do {
-                $admin_poll_id = $this->random(24);
-            } while ($this->pollRepository->existsByAdminId($admin_poll_id));
+        try {
+            if (empty($form->id)) { // User want us to generate an id for him
+                do {
+                    $poll_id = $this->random(16);
+                } while ($this->pollRepository->existsById($poll_id));
+                $admin_poll_id = $poll_id . $this->random(8);
+            } else { // User have choosen the poll id
+                $poll_id = $form->id;
+                do {
+                    $admin_poll_id = $this->random(24);
+                } while ($this->pollRepository->existsByAdminId($admin_poll_id));
+            }
+
+            // Insert poll + slots
+            $this->pollRepository->beginTransaction();
+            $this->pollRepository->insertPoll($poll_id, $admin_poll_id, $form);
+            $this->slotRepository->insertSlots($poll_id, $form->getChoices());
+            $this->pollRepository->commit();
+
+            $this->logService->log(
+                'CREATE_POLL',
+                'id:' . $poll_id . ', title: ' . $form->title . ', format:' . $form->format . ', admin:' . $form->admin_name . ', mail:' . $form->admin_mail
+            );
+
+            return [$poll_id, $admin_poll_id];
+        } catch (DBALException $e) {
+            $this->pollRepository->rollback();
+            $this->logService->log('ERROR', "Poll couldn't be saved : " . $e->getMessage());
+            return null;
         }
-
-        // Insert poll + slots
-        $this->pollRepository->beginTransaction();
-        $this->pollRepository->insertPoll($poll_id, $admin_poll_id, $form);
-        $this->slotRepository->insertSlots($poll_id, $form->getChoices());
-        $this->pollRepository->commit();
-
-        $this->logService->log('CREATE_POLL', 'id:' . $poll_id . ', title: ' . $form->title . ', format:' . $form->format . ', admin:' . $form->admin_name . ', mail:' . $form->admin_mail);
-
-        return [$poll_id, $admin_poll_id];
     }
 
     public function findAllByAdminMail($mail) {
diff --git a/bandeaux.php b/bandeaux.php
index 2d90953..83c3536 100644
--- a/bandeaux.php
+++ b/bandeaux.php
@@ -43,15 +43,6 @@ function bandeau_titre($titre)
         <hr class="trait" role="presentation" />
     </header>
     <main role="main">';
-    
-    global $connect;
-    $tables = $connect->allTables();
-    $diff = array_diff([Utils::table('comment'), Utils::table('poll'), Utils::table('slot'), Utils::table('vote')], $tables);
-    if (0 !== count($diff)) {
-        echo '<div class="alert alert-danger">' . __('Error', 'Framadate is not properly installed, please check the "INSTALL" to setup the database before continuing.') . '</div>';
-        bandeau_pied();
-        die();
-    }
 }
 
 function liste_lang()
diff --git a/create_classic_poll.php b/create_classic_poll.php
index 8318894..93eac08 100644
--- a/create_classic_poll.php
+++ b/create_classic_poll.php
@@ -51,8 +51,12 @@ if (empty($_SESSION['form']->title) || empty($_SESSION['form']->admin_name) || (
     $min_expiry_time = $pollService->minExpiryDate();
     $max_expiry_time = $pollService->maxExpiryDate();
 
-    // The poll format is AUTRE (other)
-    if ($_SESSION['form']->format !== 'A') {
+    // The poll format is other (A) if we are in this file
+    if (!isset($_SESSION['form'])) {
+        $_SESSION['form']->format = 'A';
+    }
+    // If we come from another format, we need to clear choices
+    if (isset($_SESSION['form']->format) && $_SESSION['form']->format !== 'A') {
         $_SESSION['form']->format = 'A';
         $_SESSION['form']->clearChoices();
     }
@@ -111,7 +115,7 @@ if (empty($_SESSION['form']->title) || empty($_SESSION['form']->admin_name) || (
 
         // creation message
         $sessionService->set("Framadate", "messagePollCreated", TRUE);
-        
+
         // Redirect to poll administration
         header('Location:' . Utils::getUrlSondage($admin_poll_id, true));
         exit;
diff --git a/create_date_poll.php b/create_date_poll.php
index 8d9eb91..7cc3aec 100644
--- a/create_date_poll.php
+++ b/create_date_poll.php
@@ -44,8 +44,12 @@ if (is_readable('bandeaux_local.php')) {
 $min_expiry_time = $pollService->minExpiryDate();
 $max_expiry_time = $pollService->maxExpiryDate();
 
-// The poll format is DATE
-if (isset($_SESSION['form']->format) && ($_SESSION['form']->format !== 'D')) {
+// The poll format is DATE if we are in this file
+if (!isset($_SESSION['form'])) {
+    $_SESSION['form']->format = 'D';
+}
+// If we come from another format, we need to clear choices
+if (isset($_SESSION['form']->format) && $_SESSION['form']->format !== 'D') {
     $_SESSION['form']->format = 'D';
     $_SESSION['form']->clearChoices();
 }
@@ -73,6 +77,7 @@ switch ($step) {
 
         // Prefill form->choices
         foreach ($_SESSION['form']->getChoices() as $c) {
+            /** @var Choice $c */
             $count = 3 - count($c->getSlots());
             for ($i = 0; $i < $count; $i++) {
                 $c->addSlot('');
@@ -136,7 +141,7 @@ switch ($step) {
                 if (!empty($day)) {
                     // Add choice to Form data
                     $date = DateTime::createFromFormat(__('Date', 'datetime_parseformat'), $_POST['days'][$i])->setTime(0, 0, 0);
-                    $time = $date->getTimestamp();
+                    $time = (string) $date->getTimestamp();
                     $choice = new Choice($time);
                     $_SESSION['form']->addChoice($choice);
 
@@ -155,6 +160,7 @@ switch ($step) {
         $summary = '<ul>';
         $choices = $_SESSION['form']->getChoices();
         foreach ($choices as $choice) {
+            /** @var Choice $choice */
             $summary .= '<li>' . strftime($date_format['txt_full'], $choice->getName());
             $first = true;
             foreach ($choice->getSlots() as $slots) {
@@ -235,7 +241,7 @@ switch ($step) {
 
         // creation message
         $sessionService->set("Framadate", "messagePollCreated", TRUE);
-        
+
         // Redirect to poll administration
         header('Location:' . Utils::getUrlSondage($admin_poll_id, true));
         exit;