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Co-authored-by: Lukas Bestle <[email protected]>

config/api/routes/files.php

@@ -49,7 +49,7 @@
 			// move_uploaded_file() not working with unit test
 			// @codeCoverageIgnoreStart
 			return $this->upload(function ($source, $filename) use ($path) {
-				// check if upload is  sent in chunks and handle them
+				// check if upload is sent in chunks and handle them
 				$source = Upload::chunk($this, $source, $filename);
 
 				// complete files return an absolute path;

src/Api/Upload.php

@@ -62,7 +62,7 @@ public static function chunk(
 			$offset = (int)$api->requestHeaders('Upload-Offset');
 
 			// validate various aspects of the request
-			// to ensure the chunk isn't try to do malicious actions
+			// to ensure the chunk isn't trying to do malicious actions
 			static::validateChunk(
 				source:   $source,
 				tmp:      $tmpWithId,
@@ -193,15 +193,18 @@ protected static function validateChunk(
 			if ($offset !== F::size($tmp)) {
 				throw new Exception('Chunk offset ' . $offset . ' does not match the existing tmp upload file size of ' . F::size($tmp));
 			}
-		} elseif ($offset > 0) {
-			// sent chunk is not expected to be the first part,
-			// but no tmp file to continue exists yet
-			throw new NotFoundException('Chunk offset ' . $offset . ' for non-existing tmp file: ' . $name);
-		} elseif ($offset === 0) {
+
+			// existing file is valid, done validating
+			return;
+		}
+
+		if ($offset === 0) {
 			// validate file (extension, name) for first chunk;
 			// will also be validate again by `$model->createFile()`
 			// when completely uploaded
 			FileRules::validFile($file, false);
 		}
+
+		throw new NotFoundException('Chunk offset ' . $offset . ' for non-existing tmp file: ' . $name);
 	}
 }