diff --git a/vendor/magento/module-deploy/Collector/Collector.php b/vendor/magento/module-deploy/Collector/Collector.php
index b09001a7ac04..441d165f6792 100644
--- a/vendor/magento/module-deploy/Collector/Collector.php
+++ b/vendor/magento/module-deploy/Collector/Collector.php
@@ -93,6 +93,9 @@ public function collect()
                 if ($file->getModule() && !$this->moduleManager->isEnabled($file->getModule())) {
                     continue;
                 }
+                if (!$file->getFileName()) {
+                    continue;
+                }
                 $file->setDeployedFileName($this->fileNameResolver->resolve($file->getFileName()));
                 $params = $this->getParams($file);
                 $packagePath = "{$params['area']}/{$params['theme']}/{$params['locale']}";
diff --git a/vendor/magento/module-deploy/Package/Processor/PreProcessor/Css.php b/vendor/magento/module-deploy/Package/Processor/PreProcessor/Css.php
index 152c95f86552..4ecac5339aab 100644
--- a/vendor/magento/module-deploy/Package/Processor/PreProcessor/Css.php
+++ b/vendor/magento/module-deploy/Package/Processor/PreProcessor/Css.php
@@ -135,7 +135,12 @@ private function buildMap($packagePath, $filePath, $fullPath)
             $imports = [];
             $this->map[$fullPath] = [];
 
-            $content = $this->staticDir->readFile($this->minification->addMinifiedSign($fullPath));
+            $tmpFilename = $this->minification->addMinifiedSign($fullPath);
+            if ($this->staticDir->isReadable($tmpFilename)) {
+                $content = $this->staticDir->readFile($tmpFilename);
+            } else {
+                $content = '';
+            }
 
             $callback = function ($matchContent) use ($packagePath, $filePath, &$imports) {
                 $importRelPath = $this->normalize(pathinfo($filePath, PATHINFO_DIRNAME) . '/' . $matchContent['path']);
diff --git a/vendor/magento/module-deploy/Package/Processor/PreProcessor/Less.php b/vendor/magento/module-deploy/Package/Processor/PreProcessor/Less.php
index b5fe0c78640e..6e85da62b6b2 100644
--- a/vendor/magento/module-deploy/Package/Processor/PreProcessor/Less.php
+++ b/vendor/magento/module-deploy/Package/Processor/PreProcessor/Less.php
@@ -58,6 +58,11 @@ class Less implements ProcessorInterface
      */
     private $map = [];
 
+    /**
+     * @var array
+     */
+    private $pFileCache = [];
+
     /**
      * Less constructor
      *
@@ -131,6 +136,7 @@ private function hasOverrides(PackageFile $parentFile, Package $package)
         $currentPackageFiles = array_merge($package->getFilesByType('less'), $package->getFilesByType('css'));
 
         foreach ($currentPackageFiles as $file) {
+            $this->pFileCache = [];
             if ($this->inParentFiles($file->getDeployedFileName(), $parentFile->getFileName(), $map)) {
                 return true;
             }
@@ -151,7 +157,13 @@ private function inParentFiles($fileName, $parentFile, $map)
                 return true;
             } else {
                 foreach ($map[$parentFile] as $pFile) {
-                    return $this->inParentFiles($fileName, $pFile, $map);
+                    if (in_array($pFile, $this->pFileCache)) {
+                        continue;
+                    }
+                    $this->pFileCache[] = $pFile;
+                    if ($this->inParentFiles($fileName, $pFile, $map)) {
+                        return true;
+                    }
                 }
             }
         }