diff --git a/apps/files_external/lib/Lib/Storage/AmazonS3.php b/apps/files_external/lib/Lib/Storage/AmazonS3.php
index 583981d3cb4a9..9986270a931cc 100644
--- a/apps/files_external/lib/Lib/Storage/AmazonS3.php
+++ b/apps/files_external/lib/Lib/Storage/AmazonS3.php
@@ -19,6 +19,7 @@
 use OCP\Constants;
 use OCP\Files\FileInfo;
 use OCP\Files\IMimeTypeDetector;
+use OCP\Files\NotPermittedException;
 use OCP\ICache;
 use OCP\ICacheFactory;
 use OCP\ITempManager;
@@ -790,7 +791,15 @@ public function writeStream(string $path, $stream, ?int $size = null): int {
 		}
 
 		$path = $this->normalizePath($path);
-		$this->writeObject($path, $stream, $this->mimeDetector->detectPath($path));
+		try {
+			$this->writeObject($path, $stream, $this->mimeDetector->detectPath($path));
+		} catch (S3Exception $exception) {
+			$this->logger->error($exception->getMessage(), [
+				'app' => 'files_external',
+				'exception' => $exception,
+			]);
+			throw new NotPermittedException($exception->getMessage(), $exception->getCode(), $exception);
+		}
 		$this->invalidateCache($path);
 
 		return $size;
diff --git a/lib/private/Files/Storage/Common.php b/lib/private/Files/Storage/Common.php
index d6462fe245b2e..51fbffdf15392 100644
--- a/lib/private/Files/Storage/Common.php
+++ b/lib/private/Files/Storage/Common.php
@@ -29,6 +29,7 @@
 use OCP\Files\GenericFileException;
 use OCP\Files\IFilenameValidator;
 use OCP\Files\InvalidPathException;
+use OCP\Files\NotPermittedException;
 use OCP\Files\Storage\IConstructableStorage;
 use OCP\Files\Storage\ILockingStorage;
 use OCP\Files\Storage\IStorage;
@@ -521,6 +522,9 @@ public function copyFromStorage(IStorage $sourceStorage, string $sourceInternalP
 				try {
 					$this->writeStream($targetInternalPath, $source);
 					$result = true;
+				} catch (NotPermittedException $e) {
+					Server::get(LoggerInterface::class)->warning('Failed to copy stream to storage', ['exception' => $e]);
+					throw new ForbiddenException($e->getMessage(), false, $e);
 				} catch (\Exception $e) {
 					Server::get(LoggerInterface::class)->warning('Failed to copy stream to storage', ['exception' => $e]);
 				}