diff --git a/Neos.Fusion/Classes/Core/Cache/ParserCache.php b/Neos.Fusion/Classes/Core/Cache/ParserCache.php
index 08f2a82b21a..e5a8bb166c2 100644
--- a/Neos.Fusion/Classes/Core/Cache/ParserCache.php
+++ b/Neos.Fusion/Classes/Core/Cache/ParserCache.php
@@ -58,7 +58,12 @@ public function cacheForFusionFile(?string $contextPathAndFilename, \Closure $ge
         if (str_contains($contextPathAndFilename, '://')) {
             $contextPathAndFilename = $this->getAbsolutePathForPackageRessourceUri($contextPathAndFilename);
         }
-        $identifier = $this->getCacheIdentifierForFile($contextPathAndFilename);
+        $fusionFileRealPath = realpath($contextPathAndFilename);
+        if ($fusionFileRealPath === false) {
+            // should not happen as the file would not been able to be read in the first place.
+            throw new \RuntimeException("Couldn't resolve realpath for: '$contextPathAndFilename'", 1705409467);
+        }
+        $identifier = $this->getCacheIdentifierForAbsoluteUnixStyleFilePathWithoutDirectoryTraversal($fusionFileRealPath);
         return $this->cacheForIdentifier($identifier, $generateValueToCache);
     }
 
diff --git a/Neos.Fusion/Classes/Core/Cache/ParserCacheFlusher.php b/Neos.Fusion/Classes/Core/Cache/ParserCacheFlusher.php
index 9d02094ebd0..04a4b0c13ac 100644
--- a/Neos.Fusion/Classes/Core/Cache/ParserCacheFlusher.php
+++ b/Neos.Fusion/Classes/Core/Cache/ParserCacheFlusher.php
@@ -50,7 +50,10 @@ public function flushPartialCacheOnFileChanges($fileMonitorIdentifier, array $ch
 
         $identifiersToFlush = [];
         foreach ($changedFiles as $changedFile => $status) {
-            $identifiersToFlush[] = $this->getCacheIdentifierForFile($changedFile);
+            // flow already returns absolute file paths from the file monitor, so we don't have to call realpath.
+            // attempting to use realpath can even result in an error as the file might be removed and thus no realpath can be resolved via file system.
+            // https://github.com/neos/neos-development-collection/pull/4509
+            $identifiersToFlush[] = $this->getCacheIdentifierForAbsoluteUnixStyleFilePathWithoutDirectoryTraversal($changedFile);
         }
 
         if ($identifiersToFlush !== []) {
diff --git a/Neos.Fusion/Classes/Core/Cache/ParserCacheIdentifierTrait.php b/Neos.Fusion/Classes/Core/Cache/ParserCacheIdentifierTrait.php
index 86fcf9d6a0a..23fd8a76b36 100644
--- a/Neos.Fusion/Classes/Core/Cache/ParserCacheIdentifierTrait.php
+++ b/Neos.Fusion/Classes/Core/Cache/ParserCacheIdentifierTrait.php
@@ -19,7 +19,7 @@
 trait ParserCacheIdentifierTrait
 {
     /**
-     * creates a comparable hash of the dsl type and content to be used as cache identifier
+     * Creates a comparable hash of the dsl type and content to be used as cache identifier
      */
     private function getCacheIdentifierForDslCode(string $identifier, string $code): string
     {
@@ -27,18 +27,24 @@ private function getCacheIdentifierForDslCode(string $identifier, string $code):
     }
 
     /**
-     * creates a comparable hash of the absolute, resolved $fusionFileName
+     * Creates a comparable hash of the absolute-unix-style-file-path-without-directory-traversal
      *
-     * @throws \InvalidArgumentException
+     * something like
+     *  - /Users/marc/Code/neos-project/Packages/Neos
+     *
+     * its crucial that the path
+     *  - is absolute
+     *  - the path separator is in unix style: forward-slash /
+     *  - doesn't contain directory traversal /../ or /./
+     *
+     * to be absolutely sure the path matches the criteria, {@see realpath} can be used.
+     *
+     * if the path does not match the criteria, a different hash as expected will be generated and caching will break.
      */
-    private function getCacheIdentifierForFile(string $fusionFileName): string
-    {
-        $realPath = realpath($fusionFileName);
-        if ($realPath === false) {
-            throw new \InvalidArgumentException("Couldn't resolve realpath for: '$fusionFileName'");
-        }
-
-        $realFusionFilePathWithoutRoot = str_replace(FLOW_PATH_ROOT, '', $realPath);
-        return 'file_' . md5($realFusionFilePathWithoutRoot);
+    private function getCacheIdentifierForAbsoluteUnixStyleFilePathWithoutDirectoryTraversal(
+        string $absoluteUnixStyleFilePathWithoutDirectoryTraversal
+    ): string {
+        $filePathWithoutRoot = str_replace(FLOW_PATH_ROOT, '', $absoluteUnixStyleFilePathWithoutDirectoryTraversal);
+        return 'file_' . md5($filePathWithoutRoot);
     }
 }