diff --git a/phpstan-baseline.neon b/phpstan-baseline.neon
index db1e5cddf1..004f9da8ba 100644
--- a/phpstan-baseline.neon
+++ b/phpstan-baseline.neon
@@ -585,11 +585,6 @@ parameters:
 			count: 1
 			path: src/Config/Form.php
 
-		-
-			message: "#^Unreachable statement \\- code above always terminates\\.$#"
-			count: 2
-			path: src/Config/Form.php
-
 		-
 			message: "#^Argument of an invalid type mixed supplied for foreach, only iterables are supported\\.$#"
 			count: 2
@@ -7340,11 +7335,6 @@ parameters:
 			count: 1
 			path: src/Error/Error.php
 
-		-
-			message: "#^Match expression does not handle remaining values\\: 3\\|int\\<min, \\-1\\>\\|int\\<5, 7\\>\\|int\\<9, 15\\>\\|int\\<17, 31\\>\\|int\\<33, 63\\>\\|int\\<65, 127\\>\\|int\\<129, 255\\>\\|int\\<257, 511\\>\\|int\\<513, 1023\\>\\|int\\<1025, 2047\\>\\|int\\<2049, 4095\\>\\|int\\<4097, 8191\\>\\|int\\<8193, 16383\\>\\|int\\<16385, max\\>$#"
-			count: 2
-			path: src/Error/Error.php
-
 		-
 			message: "#^Only booleans are allowed in \\|\\|, int\\<0, 18176\\> given on the right side\\.$#"
 			count: 1
@@ -14385,11 +14375,6 @@ parameters:
 			count: 1
 			path: src/Theme/Theme.php
 
-		-
-			message: "#^Unreachable statement \\- code above always terminates\\.$#"
-			count: 1
-			path: src/Theme/Theme.php
-
 		-
 			message: "#^Left side of && is always true\\.$#"
 			count: 1
@@ -14415,11 +14400,6 @@ parameters:
 			count: 1
 			path: src/Theme/ThemeManager.php
 
-		-
-			message: "#^Unreachable statement \\- code above always terminates\\.$#"
-			count: 1
-			path: src/Theme/ThemeManager.php
-
 		-
 			message: "#^Cannot access offset string on mixed\\.$#"
 			count: 2
diff --git a/psalm-baseline.xml b/psalm-baseline.xml
index 88c85faad8..f82ca3d10d 100644
--- a/psalm-baseline.xml
+++ b/psalm-baseline.xml
@@ -399,10 +399,6 @@
     <ReferenceReusedFromConfusingScope>
       <code><![CDATA[$name]]></code>
     </ReferenceReusedFromConfusingScope>
-    <UnevaluatedCode>
-      <code><![CDATA[return [];]]></code>
-      <code><![CDATA[return [];]]></code>
-    </UnevaluatedCode>
   </file>
   <file src="src/Config/FormDisplay.php">
     <DeprecatedMethod>
@@ -11269,9 +11265,6 @@
     <PossiblyUnusedProperty>
       <code><![CDATA[$filesizeInfo]]></code>
     </PossiblyUnusedProperty>
-    <UnevaluatedCode>
-      <code><![CDATA[return false;]]></code>
-    </UnevaluatedCode>
   </file>
   <file src="src/Theme/ThemeManager.php">
     <DeprecatedMethod>
@@ -11306,9 +11299,6 @@
     <RiskyTruthyFalsyComparison>
       <code><![CDATA[$cookieTheme]]></code>
     </RiskyTruthyFalsyComparison>
-    <UnevaluatedCode>
-      <code><![CDATA[return false;]]></code>
-    </UnevaluatedCode>
   </file>
   <file src="src/Tracking/Tracker.php">
     <DeprecatedMethod>
diff --git a/src/Config/Form.php b/src/Config/Form.php
index 567e6322f9..f306d4fd27 100644
--- a/src/Config/Form.php
+++ b/src/Config/Form.php
@@ -7,6 +7,9 @@ declare(strict_types=1);
 
 namespace PhpMyAdmin\Config;
 
+use PhpMyAdmin\Exceptions\UndefinedOption;
+use Webmozart\Assert\Assert;
+
 use function array_combine;
 use function array_shift;
 use function array_walk;
@@ -21,9 +24,6 @@ use function mb_strrpos;
 use function mb_substr;
 use function str_replace;
 use function str_starts_with;
-use function trigger_error;
-
-use const E_USER_ERROR;
 
 /**
  * Base class for forms, loads default configuration options, checks allowed
@@ -110,16 +110,10 @@ class Form
     {
         $value = $this->configFile->getDbEntry($optionPath);
         if ($value === null) {
-            trigger_error($optionPath . ' - select options not defined', E_USER_ERROR);
-
-            return [];
+            throw new UndefinedOption($optionPath . ' - select options not defined');
         }
 
-        if (! is_array($value)) {
-            trigger_error($optionPath . ' - not a static value list', E_USER_ERROR);
-
-            return [];
-        }
+        Assert::isArray($value, $optionPath . ' - not a static value list');
 
         // convert array('#', 'a', 'b') to array('a', 'b')
         if (isset($value[0]) && $value[0] === '#') {
diff --git a/src/Error/Error.php b/src/Error/Error.php
index 251a92c0f3..c6b40536e0 100644
--- a/src/Error/Error.php
+++ b/src/Error/Error.php
@@ -258,7 +258,7 @@ class Error extends Message
     public function getType(): string
     {
         return match ($this->errorNumber) {
-            0 => 'Internal error',
+            default => 'Internal error',
             E_ERROR => 'Error',
             E_WARNING => 'Warning',
             E_PARSE => 'Parsing Error',
@@ -285,7 +285,7 @@ class Error extends Message
     public function getLevel(): string
     {
         return match ($this->errorNumber) {
-            0 => 'error',
+            default => 'error',
             E_ERROR => 'error',
             E_WARNING => 'error',
             E_PARSE => 'error',
diff --git a/src/Exceptions/InvalidImagePath.php b/src/Exceptions/InvalidImagePath.php
new file mode 100644
index 0000000000..d725173ed0
--- /dev/null
+++ b/src/Exceptions/InvalidImagePath.php
@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpMyAdmin\Exceptions;
+
+use Exception;
+
+class InvalidImagePath extends Exception
+{
+}
diff --git a/src/Exceptions/MismatchedSessionId.php b/src/Exceptions/MismatchedSessionId.php
new file mode 100644
index 0000000000..d4e08b560f
--- /dev/null
+++ b/src/Exceptions/MismatchedSessionId.php
@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpMyAdmin\Exceptions;
+
+use Exception;
+
+class MismatchedSessionId extends Exception
+{
+}
diff --git a/src/Exceptions/MissingTheme.php b/src/Exceptions/MissingTheme.php
new file mode 100644
index 0000000000..0b39fbe352
--- /dev/null
+++ b/src/Exceptions/MissingTheme.php
@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpMyAdmin\Exceptions;
+
+use Exception;
+
+class MissingTheme extends Exception
+{
+}
diff --git a/src/Exceptions/UndefinedOption.php b/src/Exceptions/UndefinedOption.php
new file mode 100644
index 0000000000..bdb78f0b71
--- /dev/null
+++ b/src/Exceptions/UndefinedOption.php
@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpMyAdmin\Exceptions;
+
+use RuntimeException;
+
+class UndefinedOption extends RuntimeException
+{
+}
diff --git a/src/Exceptions/UnsupportedLanguageCode.php b/src/Exceptions/UnsupportedLanguageCode.php
new file mode 100644
index 0000000000..bdc2386f79
--- /dev/null
+++ b/src/Exceptions/UnsupportedLanguageCode.php
@@ -0,0 +1,11 @@
+<?php
+
+declare(strict_types=1);
+
+namespace PhpMyAdmin\Exceptions;
+
+use Exception;
+
+class UnsupportedLanguageCode extends Exception
+{
+}
diff --git a/src/Http/Middleware/TokenRequestParamChecking.php b/src/Http/Middleware/TokenRequestParamChecking.php
index fc40c35387..84313d6137 100644
--- a/src/Http/Middleware/TokenRequestParamChecking.php
+++ b/src/Http/Middleware/TokenRequestParamChecking.php
@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace PhpMyAdmin\Http\Middleware;
 
+use PhpMyAdmin\Exceptions\MismatchedSessionId;
 use PhpMyAdmin\Sanitize;
 use Psr\Http\Message\ResponseInterface;
 use Psr\Http\Message\ServerRequestInterface;
@@ -14,9 +15,6 @@ use function __;
 use function hash_equals;
 use function is_scalar;
 use function session_id;
-use function trigger_error;
-
-use const E_USER_ERROR;
 
 /**
  * Check whether user supplied token is valid, if not remove any possibly
@@ -55,11 +53,10 @@ final class TokenRequestParamChecking implements MiddlewareInterface
 
         // Warn in case the mismatch is result of failed setting of session cookie
         if (isset($_POST['set_session']) && $_POST['set_session'] !== session_id()) {
-            trigger_error(
+            throw new MismatchedSessionId(
                 __(
                     'Failed to set session cookie. Maybe you are using HTTP instead of HTTPS to access phpMyAdmin.',
                 ),
-                E_USER_ERROR,
             );
         }
 
diff --git a/src/LanguageManager.php b/src/LanguageManager.php
index 8f4e9c0ac9..b76d449971 100644
--- a/src/LanguageManager.php
+++ b/src/LanguageManager.php
@@ -4,6 +4,8 @@ declare(strict_types=1);
 
 namespace PhpMyAdmin;
 
+use PhpMyAdmin\Exceptions\UnsupportedLanguageCode;
+
 use function __;
 use function closedir;
 use function count;
@@ -14,12 +16,9 @@ use function opendir;
 use function preg_grep;
 use function readdir;
 use function strtolower;
-use function trigger_error;
 use function uasort;
 use function ucfirst;
 
-use const E_USER_ERROR;
-
 /**
  * Language selection manager
  */
@@ -957,9 +956,6 @@ class LanguageManager
             return;
         }
 
-        trigger_error(
-            __('Ignoring unsupported language code.'),
-            E_USER_ERROR,
-        );
+        throw new UnsupportedLanguageCode(__('Ignoring unsupported language code.'));
     }
 }
diff --git a/src/Theme/Theme.php b/src/Theme/Theme.php
index fa79bbd16c..1752750a00 100644
--- a/src/Theme/Theme.php
+++ b/src/Theme/Theme.php
@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace PhpMyAdmin\Theme;
 
+use PhpMyAdmin\Exceptions\InvalidImagePath;
 use PhpMyAdmin\Version;
 use Webmozart\Assert\Assert;
 use Webmozart\Assert\InvalidArgumentException;
@@ -19,12 +20,10 @@ use function is_dir;
 use function is_readable;
 use function json_decode;
 use function sprintf;
-use function trigger_error;
 use function trim;
 use function version_compare;
 
 use const DIRECTORY_SEPARATOR;
-use const E_USER_ERROR;
 
 /**
  * handles theme
@@ -176,16 +175,10 @@ class Theme
             return true;
         }
 
-        // we failed
-        trigger_error(
-            sprintf(
-                __('No valid image path for theme %s found!'),
-                $this->getName(),
-            ),
-            E_USER_ERROR,
-        );
-
-        return false;
+        throw new InvalidImagePath(sprintf(
+            __('No valid image path for theme %s found!'),
+            $this->getName(),
+        ));
     }
 
     /**
diff --git a/src/Theme/ThemeManager.php b/src/Theme/ThemeManager.php
index 6d4dc4c02a..8cc9fec3f1 100644
--- a/src/Theme/ThemeManager.php
+++ b/src/Theme/ThemeManager.php
@@ -4,24 +4,18 @@ declare(strict_types=1);
 
 namespace PhpMyAdmin\Theme;
 
+use DirectoryIterator;
 use PhpMyAdmin\Config;
 use PhpMyAdmin\Current;
+use PhpMyAdmin\Exceptions\MissingTheme;
 
 use function __;
 use function array_key_exists;
-use function closedir;
 use function htmlspecialchars;
-use function is_dir;
 use function is_string;
 use function ksort;
-use function opendir;
-use function readdir;
 use function sprintf;
-use function trigger_error;
 
-use const DIRECTORY_SEPARATOR;
-use const E_USER_ERROR;
-use const E_USER_WARNING;
 use const ROOT_PATH;
 
 /**
@@ -70,17 +64,14 @@ class ThemeManager
 
         $configThemeExists = $this->checkTheme($config->settings['ThemeDefault']);
         if (! $configThemeExists) {
-            trigger_error(
-                sprintf(
-                    __('Default theme %s not found!'),
-                    htmlspecialchars($config->settings['ThemeDefault']),
-                ),
-                E_USER_ERROR,
-            );
-        } else {
-            $this->themeDefault = $config->settings['ThemeDefault'];
+            throw new MissingTheme(sprintf(
+                __('Default theme %s not found!'),
+                htmlspecialchars($config->settings['ThemeDefault']),
+            ));
         }
 
+        $this->themeDefault = $config->settings['ThemeDefault'];
+
         // check if user have a theme cookie
         $cookieTheme = $this->getThemeCookie();
         if (
@@ -116,15 +107,10 @@ class ThemeManager
     public function setActiveTheme(string|null $theme): bool
     {
         if (! $this->checkTheme($theme)) {
-            trigger_error(
-                sprintf(
-                    __('Theme %s not found!'),
-                    htmlspecialchars((string) $theme),
-                ),
-                E_USER_ERROR,
-            );
-
-            return false;
+            throw new MissingTheme(sprintf(
+                __('Theme %s not found!'),
+                htmlspecialchars((string) $theme),
+            ));
         }
 
         $this->activeTheme = $theme;
@@ -216,24 +202,21 @@ class ThemeManager
     public function loadThemes(): void
     {
         $this->themes = [];
-        $dirHandle = opendir($this->themesPath);
 
-        if ($dirHandle === false) {
-            trigger_error('Error: cannot open themes folder: ./themes', E_USER_WARNING);
+        $directoryIterator = new DirectoryIterator($this->themesPath);
 
-            return;
-        }
-
-        while (($dir = readdir($dirHandle)) !== false) {
-            if ($dir === '.' || $dir === '..' || ! @is_dir($this->themesPath . $dir)) {
+        foreach ($directoryIterator as $directoryInfo) {
+            if ($directoryInfo->isDot() || ! $directoryInfo->isDir()) {
                 continue;
             }
 
+            $dir = $directoryInfo->getFilename();
+
             if (array_key_exists($dir, $this->themes)) {
                 continue;
             }
 
-            $newTheme = Theme::load($this->themesPathUrl . $dir, $this->themesPath . $dir . DIRECTORY_SEPARATOR, $dir);
+            $newTheme = Theme::load($this->themesPathUrl . $dir, $this->themesPath . $dir . '/', $dir);
             if (! $newTheme instanceof Theme) {
                 continue;
             }
@@ -241,7 +224,6 @@ class ThemeManager
             $this->themes[$dir] = $newTheme;
         }
 
-        closedir($dirHandle);
         ksort($this->themes);
     }
 
@@ -278,7 +260,7 @@ class ThemeManager
      */
     public static function getThemesFsDir(): string
     {
-        return ROOT_PATH . 'public/themes' . DIRECTORY_SEPARATOR;
+        return ROOT_PATH . 'public/themes/';
     }
 
     /**