From 0663f79640ec69a4b2249db5d7c13bbaa02f51db Mon Sep 17 00:00:00 2001
From: Uwe Steinmann <steinm@debian.org>
Date: Thu, 2 Apr 2026 10:16:29 +0200
Subject: [PATCH] do not call mb_convert_encoding() if encoding is unknown

---
 inc/inc.ClassConversionServiceTextToText.php | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/inc/inc.ClassConversionServiceTextToText.php b/inc/inc.ClassConversionServiceTextToText.php
index d84e0473e..f8b8dbd43 100644
--- a/inc/inc.ClassConversionServiceTextToText.php
+++ b/inc/inc.ClassConversionServiceTextToText.php
@@ -57,7 +57,8 @@ class SeedDMS_ConversionServiceTextToText extends SeedDMS_ConversionServiceBase
 		$encoding  = $this->detect_utf_encoding($content);
 		// mb_detect_encoding() is not a good as detect_utf_encoding()
 		// $encoding  = mb_detect_encoding($content);
-		$content = mb_convert_encoding($content, 'utf8', $encoding);
+		if ($encoding)
+			$content = mb_convert_encoding($content, 'utf8', $encoding);
 		if($target) {
 			file_put_contents($target, $content);
 			return true;