diff --git a/common.php b/common.php
index a89a8484..8bedc808 100644
--- a/common.php
+++ b/common.php
@@ -88,7 +88,7 @@ if (!empty($CONF['language_hook']) && function_exists($CONF['language_hook'])) {
 Config::write('__LANG', $PALANG);
 
 if (!defined('POSTFIXADMIN_CLI')) {
-    if (!isset($CONF) || !isset($PALANG)) {
+    if (!isset($PALANG)) {
         die("environment not setup correctly");
     }
     require_once(__DIR__  . '/lib/smarty/libs/Autoloader.php');
diff --git a/composer.json b/composer.json
index ce6ad788..48095351 100644
--- a/composer.json
+++ b/composer.json
@@ -16,7 +16,7 @@
         "lint": "@php ./vendor/bin/parallel-lint --exclude vendor/ --exclude lib/block_random_int.php --exclude lib/array_column.php .",
         "test": "@php ./vendor/bin/phpunit --coverage-clover ./clover.xml tests/",
         "test-fixup": "mkdir -p templates_c ; test -f config.local.php || touch config.local.php",
-        "psalm": "@php ./vendor/bin/psalm --show-info=false "
+        "psalm": "@php ./vendor/bin/psalm --no-cache --show-info=false "
     },
     "require": {
         "php": ">=7.0"
diff --git a/model/Login.php b/model/Login.php
index 5a9ae8fe..80abbba6 100644
--- a/model/Login.php
+++ b/model/Login.php
@@ -36,7 +36,7 @@ class Login {
                 $crypt_password = pacrypt($password, $row['password']);
             } catch (\Exception $e) {
                 error_log("Error while trying to call pacrypt()");
-                error_log($e);
+                error_log("" . $e);
                 hash_equals("not", "comparable");
                 return false; // just refuse to login?
             }
@@ -49,7 +49,7 @@ class Login {
             $x = pacrypt('abc', 'def');
         } catch (\Exception $e) {
             error_log("Error trying to call pacrypt()");
-            error_log($e);
+            error_log("" . $e);
         }
 
         return hash_equals('not', 'comparable');
diff --git a/psalm.xml b/psalm.xml
index ebf0cc59..3fca0ec0 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -1,6 +1,7 @@
 <?xml version="1.0"?>
 <psalm
-    errorLevel="5"
+    phpVersion="7.4"
+    errorLevel="4"
     resolveFromConfigFile="true"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="https://getpsalm.org/schema/config"
@@ -35,4 +36,5 @@
         <LessSpecificReturnType errorLevel="info"/>
 
     </issueHandlers>
+
 </psalm>
diff --git a/public/list-virtual.php b/public/list-virtual.php
index ae98ca8b..ed8e112a 100644
--- a/public/list-virtual.php
+++ b/public/list-virtual.php
@@ -49,10 +49,6 @@ if (isset($_POST['search']) && is_array($_POST['search'])) {
     $search = $_GET['search'];
 }
 
-if (!is_array($search)) {
-    die(Config::Lang('invalid_parameter'));
-}
-
 if (count($list_domains) == 0) {
     if (authentication_has_role('global-admin')) {
         flash_error($PALANG['no_domains_exist']);
diff --git a/public/setup.php b/public/setup.php
index fad981a2..a83508bb 100644
--- a/public/setup.php
+++ b/public/setup.php
@@ -545,7 +545,7 @@ function create_admin($values) {
 }
 
 /**
- * @return array['info' => string[], 'warn' => string[], 'error' => string[] ]
+ * @return array like: ['info' => string[], 'warn' => string[], 'error' => string[] ]
  */
 function do_software_environment_check() {
     $CONF = Config::getInstance()->getAll();
diff --git a/public/users/password-recover.php b/public/users/password-recover.php
index 5a4d170b..19b29232 100644
--- a/public/users/password-recover.php
+++ b/public/users/password-recover.php
@@ -108,7 +108,7 @@ if ($_SERVER['REQUEST_METHOD'] === "POST") {
     // throttle password reset requests to prevent brute force attack
     $elapsed_time = microtime(true) - $start_time;
     if ($elapsed_time < 2 * pow(10, 6)) {
-        usleep(2 * pow(10, 6) - $elapsed_time);
+        usleep( (int) ( 2 * pow(10, 6) - $elapsed_time ) );
     }
 
     flash_info(Config::Lang('pPassword_recovery_processed'));
diff --git a/public/vacation.php b/public/vacation.php
index 011e0e76..36558c01 100644
--- a/public/vacation.php
+++ b/public/vacation.php
@@ -142,7 +142,7 @@ if ($_SERVER['REQUEST_METHOD'] == "POST") {
     }
 
     if (isset($choice_of_reply[$tInterval_Time])) {
-        $fInterval_Time = $tInterval_Time;
+        $fInterval_Time = (int) $tInterval_Time;
     } else {
         $fInterval_Time = 0;
     }