From f89279fc4bd33d47623284ad337d3bc5aa6dd282 Mon Sep 17 00:00:00 2001
From: chino <chino@users.noreply.github.com>
Date: Mon, 5 Oct 2026 19:19:09 -0400
Subject: Backport pull request #18283 from jellyfin/release-12.z

Fix EPUB metadata and covers not loading on Windows

Original-merge: 56989b0c8057275b38805ab977e1f1fa7c6d3e95

Merged-by: crobibero <cody@robibe.ro>

Backported-by: Cody Robibero <cody@robibe.ro>
---
 CONTRIBUTORS.md                                    |  1 +
 .../Books/OpenPackagingFormat/EpubImageProvider.cs |  3 +-
 .../Books/OpenPackagingFormat/EpubUtils.cs         |  3 +-
 .../Books/EpubUtilsTests.cs                        | 34 ++++++++++++++++++++++
 4 files changed, 38 insertions(+), 3 deletions(-)
 create mode 100644 tests/Jellyfin.Providers.Tests/Books/EpubUtilsTests.cs

diff --git a/CONTRIBUTORS.md b/CONTRIBUTORS.md
index 8240b458e6..31cef1437e 100644
--- a/CONTRIBUTORS.md
+++ b/CONTRIBUTORS.md
@@ -246,6 +246,7 @@
  - [Mateus Bandeira](https://github.com/mateusbandeiraa)
  - [excelsior](https://github.com/excelsior-dev)
  - [TheDreadPirate](https://github.com/thedreaddpirate)
+ - [Daniel Aquino](https://github.com/chino)
  - [klizas](https://github.com/klizas)
 
 # Emby Contributors
diff --git a/MediaBrowser.Providers/Books/OpenPackagingFormat/EpubImageProvider.cs b/MediaBrowser.Providers/Books/OpenPackagingFormat/EpubImageProvider.cs
index 69cae77628..dbd8b28198 100644
--- a/MediaBrowser.Providers/Books/OpenPackagingFormat/EpubImageProvider.cs
+++ b/MediaBrowser.Providers/Books/OpenPackagingFormat/EpubImageProvider.cs
@@ -64,7 +64,8 @@ namespace MediaBrowser.Providers.Books.OpenPackagingFormat
             }
 
             var cover = coverReference.Value;
-            var coverFile = epub.GetEntry(cover.Path);
+            // ZIP entry names always use '/', but the cover path is built with Path.Combine, which uses '\' on Windows
+            var coverFile = epub.GetEntry(cover.Path.Replace('\\', '/'));
 
             if (coverFile == null)
             {
diff --git a/MediaBrowser.Providers/Books/OpenPackagingFormat/EpubUtils.cs b/MediaBrowser.Providers/Books/OpenPackagingFormat/EpubUtils.cs
index e5d2987312..d60b50701e 100644
--- a/MediaBrowser.Providers/Books/OpenPackagingFormat/EpubUtils.cs
+++ b/MediaBrowser.Providers/Books/OpenPackagingFormat/EpubUtils.cs
@@ -1,4 +1,3 @@
-using System.IO;
 using System.IO.Compression;
 using System.Linq;
 using System.Xml.Linq;
@@ -17,7 +16,7 @@ namespace MediaBrowser.Providers.Books.OpenPackagingFormat
         /// <returns>The content file path.</returns>
         public static string? ReadContentFilePath(ZipArchive epub)
         {
-            var container = epub.GetEntry(Path.Combine("META-INF", "container.xml"));
+            var container = epub.GetEntry("META-INF/container.xml");
             if (container == null)
             {
                 return null;
diff --git a/tests/Jellyfin.Providers.Tests/Books/EpubUtilsTests.cs b/tests/Jellyfin.Providers.Tests/Books/EpubUtilsTests.cs
new file mode 100644
index 0000000000..a5a3af6210
--- /dev/null
+++ b/tests/Jellyfin.Providers.Tests/Books/EpubUtilsTests.cs
@@ -0,0 +1,34 @@
+using System.IO;
+using System.IO.Compression;
+using System.Text;
+using MediaBrowser.Providers.Books.OpenPackagingFormat;
+using Xunit;
+
+namespace Jellyfin.Providers.Tests.Books;
+
+public class EpubUtilsTests
+{
+    [Fact]
+    public void ReadContentFilePath_ReadsRootFileFromContainer()
+    {
+        using var stream = new MemoryStream();
+        using (var archive = new ZipArchive(stream, ZipArchiveMode.Create, true))
+        {
+            using var writer = new StreamWriter(archive.CreateEntry("META-INF/container.xml").Open(), Encoding.UTF8);
+            writer.Write(
+                """
+                <?xml version="1.0"?>
+                <container version="1.0" xmlns="urn:oasis:names:tc:opendocument:xmlns:container">
+                  <rootfiles>
+                    <rootfile full-path="OEBPS/content.opf" media-type="application/oebps-package+xml"/>
+                  </rootfiles>
+                </container>
+                """);
+        }
+
+        stream.Position = 0;
+        using var epub = new ZipArchive(stream, ZipArchiveMode.Read);
+
+        Assert.Equal("OEBPS/content.opf", EpubUtils.ReadContentFilePath(epub));
+    }
+}
-- 
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