diff --git a/pkg/files/files.go b/pkg/files/files.go
index 383c2ccd4..9b777f2dd 100644
--- a/pkg/files/files.go
+++ b/pkg/files/files.go
@@ -85,12 +85,12 @@ func (f *File) LoadFileMetaByID() (err error) {
 }
 
 // Create creates a new file from an FileHeader
-func Create(f io.Reader, realname string, realsize uint64, a web.Auth) (file *File, err error) {
+func Create(f io.ReadSeeker, realname string, realsize uint64, a web.Auth) (file *File, err error) {
 	return CreateWithMime(f, realname, realsize, a, "")
 }
 
 // CreateWithMime creates a new file from an FileHeader and sets its mime type
-func CreateWithMime(f io.Reader, realname string, realsize uint64, a web.Auth, mime string) (file *File, err error) {
+func CreateWithMime(f io.ReadSeeker, realname string, realsize uint64, a web.Auth, mime string) (file *File, err error) {
 	s := db.NewSession()
 	defer s.Close()
 
@@ -102,7 +102,7 @@ func CreateWithMime(f io.Reader, realname string, realsize uint64, a web.Auth, m
 	return
 }
 
-func CreateWithMimeAndSession(s *xorm.Session, f io.Reader, realname string, realsize uint64, a web.Auth, mime string, checkFileSizeLimit bool) (file *File, err error) {
+func CreateWithMimeAndSession(s *xorm.Session, f io.ReadSeeker, realname string, realsize uint64, a web.Auth, mime string, checkFileSizeLimit bool) (file *File, err error) {
 	if realsize > config.GetMaxFileSizeInMBytes()*uint64(datasize.MB) && checkFileSizeLimit {
 		return nil, ErrFileIsTooLarge{Size: realsize}
 	}
@@ -154,23 +154,25 @@ func (f *File) Delete(s *xorm.Session) (err error) {
 }
 
 // writeToStorage writes content to the given path, handling both local and S3 backends
-func writeToStorage(path string, content io.Reader, size uint64) error {
+func writeToStorage(path string, content io.ReadSeeker, size uint64) error {
 	if s3Client == nil {
 		return afs.WriteReader(path, content)
 	}
 
-	body, contentLength, cleanup, err := prepareS3UploadBody(content, size)
+	contentLength, err := contentLengthFromReadSeeker(content, size)
 	if err != nil {
-		return err
+		return fmt.Errorf("failed to determine S3 upload content length: %w", err)
 	}
-	if cleanup != nil {
-		defer cleanup()
+
+	_, err = content.Seek(0, io.SeekStart)
+	if err != nil {
+		return fmt.Errorf("failed to seek S3 upload body to start: %w", err)
 	}
 
 	_, err = s3Client.PutObject(context.Background(), &s3.PutObjectInput{
 		Bucket:        aws.String(s3Bucket),
 		Key:           aws.String(path),
-		Body:          body,
+		Body:          content,
 		ContentLength: aws.Int64(contentLength),
 	})
 	if err != nil {
@@ -180,7 +182,7 @@ func writeToStorage(path string, content io.Reader, size uint64) error {
 }
 
 // Save saves a file to storage
-func (f *File) Save(fcontent io.Reader) error {
+func (f *File) Save(fcontent io.ReadSeeker) error {
 	err := writeToStorage(f.getAbsoluteFilePath(), fcontent, f.Size)
 	if err != nil {
 		return fmt.Errorf("failed to save file: %w", err)
@@ -188,54 +190,6 @@ func (f *File) Save(fcontent io.Reader) error {
 	return keyvalue.IncrBy(metrics.FilesCountKey, 1)
 }
 
-func prepareS3UploadBody(fcontent io.Reader, expectedSize uint64) (body io.ReadSeeker, contentLength int64, cleanup func(), err error) {
-	if seeker, ok := fcontent.(io.ReadSeeker); ok {
-		contentLength, err = contentLengthFromReadSeeker(seeker, expectedSize)
-		if err != nil {
-			return nil, 0, nil, fmt.Errorf("failed to determine S3 upload content length: %w", err)
-		}
-
-		_, err = seeker.Seek(0, io.SeekStart)
-		if err != nil {
-			return nil, 0, nil, fmt.Errorf("failed to seek S3 upload body to start: %w", err)
-		}
-
-		return seeker, contentLength, nil, nil
-	}
-
-	tempFile, tempPath, err := createS3TempFile()
-	if err != nil {
-		return nil, 0, nil, fmt.Errorf("failed to create temp file for S3 upload: %w", err)
-	}
-
-	cleanup = func() {
-		_ = tempFile.Close()
-		_ = os.Remove(tempPath)
-	}
-
-	written, err := io.Copy(tempFile, fcontent)
-	if err != nil {
-		cleanup()
-		return nil, 0, nil, fmt.Errorf("failed to buffer S3 upload to temp file: %w", err)
-	}
-
-	if expectedSize > 0 {
-		if expectedSize > uint64(math.MaxInt64) {
-			log.Warningf("File size mismatch for S3 upload: expected size %d bytes does not fit into int64", expectedSize)
-		} else if written != int64(expectedSize) {
-			log.Warningf("File size mismatch for S3 upload: expected %d bytes but buffered %d bytes", expectedSize, written)
-		}
-	}
-
-	_, err = tempFile.Seek(0, io.SeekStart)
-	if err != nil {
-		cleanup()
-		return nil, 0, nil, fmt.Errorf("failed to seek temp file for S3 upload: %w", err)
-	}
-
-	return tempFile, written, cleanup, nil
-}
-
 func contentLengthFromReadSeeker(seeker io.ReadSeeker, expectedSize uint64) (int64, error) {
 	currentOffset, err := seeker.Seek(0, io.SeekCurrent)
 	if err != nil {
@@ -258,30 +212,3 @@ func contentLengthFromReadSeeker(seeker io.ReadSeeker, expectedSize uint64) (int
 
 	return endOffset, nil
 }
-
-func createS3TempFile() (file *os.File, path string, err error) {
-	dir := config.FilesS3TempDir.GetString()
-
-	tryCreate := func(tempDir string) (*os.File, error) {
-		return os.CreateTemp(tempDir, "vikunja-s3-upload-*")
-	}
-
-	if dir != "" {
-		file, err = tryCreate(dir)
-		if err == nil {
-			return file, file.Name(), nil
-		}
-	}
-
-	file, err = tryCreate("")
-	if err == nil {
-		return file, file.Name(), nil
-	}
-
-	file, err = tryCreate(".")
-	if err != nil {
-		return nil, "", err
-	}
-
-	return file, file.Name(), nil
-}