diff --git a/src/Core/Config/Adapter/JITConfigAdapter.php b/src/Core/Config/Adapter/JITConfigAdapter.php
index 5d06dc2b3e..c0d680d2c9 100644
--- a/src/Core/Config/Adapter/JITConfigAdapter.php
+++ b/src/Core/Config/Adapter/JITConfigAdapter.php
@@ -33,10 +33,13 @@ class JITConfigAdapter extends AbstractDbaConfigAdapter implements IConfigAdapte
 
 		$configs = DBA::select('config', ['v', 'k'], ['cat' => $cat]);
 		while ($config = DBA::fetch($configs)) {
-			$key = $config['k'];
+			$key   = $config['k'];
+			$value = $config['v'];
 
-			$return[$key] = $config['v'];
-			$this->in_db[$cat][$key] = true;
+			if (isset($value) && $value !== '') {
+				$return[$key] = $value;
+				$this->in_db[$cat][$key] = true;
+			}
 		}
 		DBA::close($configs);
 
diff --git a/src/Core/Config/Adapter/JITPConfigAdapter.php b/src/Core/Config/Adapter/JITPConfigAdapter.php
index d3c38623b4..4485ee5df9 100644
--- a/src/Core/Config/Adapter/JITPConfigAdapter.php
+++ b/src/Core/Config/Adapter/JITPConfigAdapter.php
@@ -29,10 +29,12 @@ class JITPConfigAdapter extends AbstractDbaConfigAdapter implements IPConfigAdap
 		if (DBA::isResult($pconfigs)) {
 			while ($pconfig = DBA::fetch($pconfigs)) {
 				$key = $pconfig['k'];
+				$value = $pconfig['v'];
 
-				$return[$key] = $pconfig['v'];
-
-				$this->in_db[$uid][$cat][$key] = true;
+				if (isset($value) && $value !== '') {
+					$return[$key] = $value;
+					$this->in_db[$uid][$cat][$key] = true;
+				}
 			}
 		} else if ($cat != 'config') {
 			// Negative caching
diff --git a/src/Core/Config/Adapter/PreloadConfigAdapter.php b/src/Core/Config/Adapter/PreloadConfigAdapter.php
index b1866a259d..d4ce6406b4 100644
--- a/src/Core/Config/Adapter/PreloadConfigAdapter.php
+++ b/src/Core/Config/Adapter/PreloadConfigAdapter.php
@@ -32,7 +32,10 @@ class PreloadConfigAdapter extends AbstractDbaConfigAdapter implements IConfigAd
 
 		$configs = DBA::select('config', ['cat', 'v', 'k']);
 		while ($config = DBA::fetch($configs)) {
-			$return[$config['cat']][$config['k']] = $config['v'];
+			$value = $config['v'];
+			if (isset($value) && $value !== '') {
+				$return[$config['cat']][$config['k']] = $value;
+			}
 		}
 		DBA::close($configs);
 
diff --git a/src/Core/Config/Adapter/PreloadPConfigAdapter.php b/src/Core/Config/Adapter/PreloadPConfigAdapter.php
index 857f2b1766..090d0f5c6f 100644
--- a/src/Core/Config/Adapter/PreloadPConfigAdapter.php
+++ b/src/Core/Config/Adapter/PreloadPConfigAdapter.php
@@ -44,7 +44,10 @@ class PreloadPConfigAdapter extends AbstractDbaConfigAdapter implements IPConfig
 
 		$pconfigs = DBA::select('pconfig', ['cat', 'v', 'k'], ['uid' => $uid]);
 		while ($pconfig = DBA::fetch($pconfigs)) {
-			$return[$pconfig['cat']][$pconfig['k']] = $pconfig['v'];
+			$value = $pconfig['v'];
+			if (isset($value) && $value !== '') {
+				$return[$pconfig['cat']][$pconfig['k']] = $value;
+			}
 		}
 		DBA::close($pconfigs);
 
diff --git a/src/Core/Config/Cache/ConfigCache.php b/src/Core/Config/Cache/ConfigCache.php
index 54da327dba..4ebcc87482 100644
--- a/src/Core/Config/Cache/ConfigCache.php
+++ b/src/Core/Config/Cache/ConfigCache.php
@@ -36,11 +36,12 @@ class ConfigCache implements IConfigCache, IPConfigCache
 				$keys = array_keys($config[$category]);
 
 				foreach ($keys as $key) {
-					if (isset($config[$category][$key])) {
+					$value = $config[$category][$key];
+					if (isset($value) && $value !== '!<unset>!') {
 						if ($overwrite) {
-							$this->set($category, $key, $config[$category][$key]);
+							$this->set($category, $key, $value);
 						} else {
-							$this->setDefault($category, $key, $config[$category][$key]);
+							$this->setDefault($category, $key, $value);
 						}
 					}
 				}
@@ -132,9 +133,19 @@ class ConfigCache implements IConfigCache, IPConfigCache
 	 */
 	public function loadP($uid, array $config)
 	{
-		foreach ($config as $category => $values) {
-			foreach ($values as $key => $value) {
-				$this->setP($uid, $category, $key, $value);
+		$categories = array_keys($config);
+
+		foreach ($categories as $category) {
+			if (isset($config[$category]) && is_array($config[$category])) {
+
+				$keys = array_keys($config[$category]);
+
+				foreach ($keys as $key) {
+					$value = $config[$category][$key];
+					if (isset($value) && $value !== '!<unset>!') {
+						$this->setP($uid, $category, $key, $value);
+					}
+				}
 			}
 		}
 	}