diff --git a/lib/Db/TimelineWrite.php b/lib/Db/TimelineWrite.php
index 68004b1e..ff871305 100644
--- a/lib/Db/TimelineWrite.php
+++ b/lib/Db/TimelineWrite.php
@@ -91,6 +91,11 @@ class TimelineWrite
             throw new \Exception('No EXIF data could be read: '.$file->getPath());
         }
 
+        // Check if MIMEType was not detected
+        if (empty($exif['MIMEType'] ?? null)) {
+            throw new \Exception('No MIMEType in EXIF data: '.$file->getPath());
+        }
+
         // Hand off if Live Photo video part
         if ($isvideo && $this->livePhoto->isVideoPart($exif)) {
             $this->livePhoto->processVideoPart($file, $exif);
diff --git a/lib/Exif.php b/lib/Exif.php
index 1011a061..68f0255d 100644
--- a/lib/Exif.php
+++ b/lib/Exif.php
@@ -149,7 +149,7 @@ class Exif
         $exifDate = $exif['DateTimeOriginal'] ?? $exif['CreateDate'] ?? null;
 
         // For videos, prefer CreateDate for timezone (QuickTimeUTC=1)
-        if (preg_match('/^video\/\w+/', (string) $exif['MIMEType'])) {
+        if (preg_match('/^video\/\w+/', (string) ($exif['MIMEType'] ?? null))) {
             $exifDate = $exif['CreateDate'] ?? $exifDate;
         }