google.protobuf.message.DecodeError: Unexpected end-group tag

[KodywithaK]

Describe the bug

This past week the develop branch / mobile api stopped working for me, tracing back to this error: google.protobuf.message.DecodeError: Unexpected end-group tag.

So now mloader is unable to download free app exclusive chapters / re-editions / etc.

web api / master branch still works as intended

Expected behavior

Download chapter(s) using mobile api

Stack trace

google.protobuf.message.DecodeError: Unexpected end-group tag

18.02.2026 12:46:30 |   INFO   |  __main__.py   202  | Started export
18.02.2026 12:46:31 |  ERROR   |  __main__.py   218  | Failed to download manga
Traceback (most recent call last):
  File "C:\Users\WDAGUtilityAccount\Desktop\mloader_mobile\mloader\__main__.py", line 210, in main
    loader.download(
    ~~~~~~~~~~~~~~~^
        title_ids=titles,
        ^^^^^^^^^^^^^^^^^
    ...<3 lines>...
        last_chapter=last,
        ^^^^^^^^^^^^^^^^^^
    )
    ^
  File "C:\Users\WDAGUtilityAccount\Desktop\mloader_mobile\mloader\loader.py", line 191, in download
    manga_list = self._normalize_ids(
        title_ids, chapter_ids, min_chapter, max_chapter, last_chapter
    )
  File "C:\Users\WDAGUtilityAccount\Desktop\mloader_mobile\mloader\loader.py", line 111, in _normalize_ids
    details = self._get_title_details(tid)
  File "C:\Users\WDAGUtilityAccount\Desktop\mloader_mobile\mloader\loader.py", line 76, in _get_title_details
    return Response.FromString(resp.content).success.title_detail_view
           ~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
  File "C:\Users\WDAGUtilityAccount\AppData\Local\Programs\Python\Python314\Lib\site-packages\google\protobuf\internal\python_message.py", line 801, in FromString
    message.MergeFromString(s)
    ~~~~~~~~~~~~~~~~~~~~~~~^^^
  File "C:\Users\WDAGUtilityAccount\AppData\Local\Programs\Python\Python314\Lib\site-packages\google\protobuf\internal\python_message.py", line 1131, in MergeFromString
    raise message_mod.DecodeError('Unexpected end-group tag.')
google.protobuf.message.DecodeError: Unexpected end-group tag.
18.02.2026 12:46:31 |   INFO   |  __main__.py   219  | SUCCESS

Environment (please complete the following information):

• OS:

  • Windows 11 x64

• Python version:

  • python 3.14.3 x64

• mloader version:

  • 1.1.10 (develop)

• Mangaplus URL:

  • https://mangaplus.shueisha.co.jp/titles/200009

[l0westbob]

Hey @KodywithaK , i dont know if hurlenko will ever read this, but i just updated my fork of mloader (I also opened a PR here in the repo).

It should totally support your task and if you are fast you might find a surprise thats still valid until the 1st of march 2026 hehe

[KodywithaK]

Hi @l0westbob, I appreciate you reaching out !

Unfortunately, I seem to be having a similar problem with your fork as well

It can find & list all the title IDs with mloader --all --language <LANGUAGE> --list-only, but not return the title details for me

For example:

: git clone https://github.com/l0westbob/mloader.git
: cd mloader
: python -m venv .venv
: .venv\Scripts\activate
: (.venv) pip install -e .[dev]
(.venv) C:\Users\WDAGUtilityAccount\Desktop\mloader>mloader https://mangaplus.shueisha.co.jp/viewer/102277 --capture-api "C:\Users\WDAGUtilityAccount\Desktop\mloader\mloader_downloads\--capture-api"

            _                 _
  _ __ ___ | | ___   __ _  __| | ___ _ __
 | '_ ` _ \| |/ _ \ / _` |/ _` |/ _ \ '__|
 | | | | | | | (_) | (_| | (_| |  __/ |
 |_| |_| |_|_|\___/ \__,_|\__,_|\___|_|


26.02.2026 00:23:43 |   INFO   |    main.py     396  | Started export
26.02.2026 00:23:44 |   INFO   | downloader.py  140  | 1/1) Manga:
26.02.2026 00:23:44 |   INFO   | downloader.py  141  |     Author:
26.02.2026 00:23:44 |   INFO   | downloader.py  324  |     Found 0 existing chapter files in 'mloader_downloads'.
26.02.2026 00:23:44 |   INFO   | downloader.py  170  |     All chapters for '' are already downloaded.
Download summary: downloaded=0, skipped_manifest=0, failed=0
26.02.2026 00:23:44 |   INFO   |    main.py     434  | SUCCESS

0001_manga_viewer_102277.pb

��
�c
�Invalid Parameter�EThere are issues connecting to Manga+. Please try again later.(10512)*�
�Close�O
�Invalid Parameter�1Por favor, inténtelo de nuevo más tarde.(10512)*�
�Cerca*c
�Invalid Parameter�EThere are issues connecting to Manga+. Please try again later.(10512)*�
�Close*Q
�Invalid Parameter�1Por favor, inténtelo de nuevo más tarde.(10512)*�
�Cerca0�*��
�Invalid Parameter�oUn problème est survenu lors de la tentative de connexion à MANGA Plus. Veuillez réessayer plus tard.(10512)*�
�Fermer0�*|
�Invalid Parameter�ZTerdapat masalah saat menyambungkan ke MANGA Plus. Silakan coba beberapa saat lagi.(10512)*	
�Menutup0�*��
�Invalid Parameter�eOcorreu um problema ao tentar se conectar à MANGA Plus. Por favor tente novamente mais tarde.(10512)*�
�Fechar0�*��
�Invalid Parameter�|Не получается присоединиться к серверу MANGA Plus. Попробуйте позже.(10512)*�
�закрытия0�*��
�Invalid Parameter�_กรุณาลองใหม่อีกครั้งในภายหลัง.(10512)*�
	ปิด0�*��
�Invalid Parameter�lBei der Verbindung mit „MANGA Plus“ ist ein Fehler aufgetreten. Bitte versuche es später erneut.(10512)*

Schließen0�*x
�Invalid Parameter�VĐang có lỗi kết nối tới MANGA Plus. Vui lòng thử lại sau.(10512)*	
�Đóng0	

0001_manga_viewer_102277.response.json

{}

And roughly the same for the title_detailV3 files as well

[l0westbob]

@KodywithaK Thanks for reporting the issue you are having. I tried to use the information you gave and i can reproduce this. There is just one issue with your provided viewer link: https://mangaplus.shueisha.co.jp/viewer/102277

It loads an empty page without any pages to view:

So could you please tell me the Title-IDs you try to download and also the language you want? This would hgelp me to reproduce this more easily and maybe also fix this issue (if there is an issue).

To be honest i was quite surprised that you had problems, because i didnt have trouble downloading any. Then i looked at my readme and saw it is using the link you have provided (mloader https://mangaplus.shueisha.co.jp/viewer/102277) and thats just beause i used dummy IDs at the beginning and then just did a regex replace of these dummy IDs in the readme, which resulted in this viewer link thats not even valid. Thanks for pointing that out and i will just fix the provided link.

[KodywithaK]

@l0westbob That makes more sense why 102277 didn't pull up anything, being a dummy ID after all haha

I retried with the latest commit, proper title/viewer IDs and got a slightly different result:
Error: Download request failed: MangaPlus API returned no <title_detail_view/manga_viewer> payload.

Command Prompt Output

: git clone https://github.com/l0westbob/mloader.git
: cd mloader
: python -m venv .venv
: .venv\Scripts\activate
: (.venv) pip install -e .[dev]
(.venv) C:\Users\WDAGUtilityAccount\Desktop\mloader>cls && FOR %T IN (titles/100011 viewer/1000762 titles/200010 viewer/2000599 titles/100020 viewer/1000486 titles/200016 viewer/2000767 titles/100079 viewer/1006150 titles/100149 viewer/1009174 titles/100140 viewer/1008831 titles/700005 viewer/7000036 titles/800001 viewer/8000017 titles/1000001 viewer/10000001) DO mloader https://mangaplus.shueisha.co.jp/%T --capture-api "R:\mloader\mloader_downloads\--capture-api\%T"

(.venv) C:\Users\WDAGUtilityAccount\Desktop\mloader>mloader https://mangaplus.shueisha.co.jp/titles/100011 --capture-api "C:\Users\WDAGUtilityAccount\Desktop\mloader\mloader_downloads\--capture-api\titles/100011"

            _                 _
  _ __ ___ | | ___   __ _  __| | ___ _ __
 | '_ ` _ \| |/ _ \ / _` |/ _` |/ _ \ '__|
 | | | | | | | (_) | (_| | (_| |  __/ |
 |_| |_| |_|_|\___/ \__,_|\__,_|\___|_|


27.02.2026 18:20:43 |   INFO   |    main.py     396  | Started export
Error: Download request failed: MangaPlus API returned no title_detail_view payload.

(.venv) C:\Users\WDAGUtilityAccount\Desktop\mloader>mloader https://mangaplus.shueisha.co.jp/viewer/1000762 --capture-api "C:\Users\WDAGUtilityAccount\Desktop\mloader\mloader_downloads\--capture-api\viewer/1000762"

            _                 _
  _ __ ___ | | ___   __ _  __| | ___ _ __
 | '_ ` _ \| |/ _ \ / _` |/ _` |/ _ \ '__|
 | | | | | | | (_) | (_| | (_| |  __/ |
 |_| |_| |_|_|\___/ \__,_|\__,_|\___|_|


27.02.2026 18:20:44 |   INFO   |    main.py     396  | Started export
Error: Download request failed: MangaPlus API returned no manga_viewer payload.

REM ------------------------------------------------------- The rest of the attempts -------------------------------------------------------

(.venv) C:\Users\WDAGUtilityAccount\Desktop\mloader>mloader https://mangaplus.shueisha.co.jp/titles/200010 --capture-api "C:\Users\WDAGUtilityAccount\Desktop\mloader\mloader_downloads\--capture-api\titles/200010"

            _                 _
  _ __ ___ | | ___   __ _  __| | ___ _ __
 | '_ ` _ \| |/ _ \ / _` |/ _` |/ _ \ '__|
 | | | | | | | (_) | (_| | (_| |  __/ |
 |_| |_| |_|_|\___/ \__,_|\__,_|\___|_|


27.02.2026 18:21:08 |   INFO   |    main.py     396  | Started export
Error: Download request failed: MangaPlus API returned no title_detail_view payload.

(.venv) C:\Users\WDAGUtilityAccount\Desktop\mloader>mloader https://mangaplus.shueisha.co.jp/viewer/10000001 --capture-api "C:\Users\WDAGUtilityAccount\Desktop\mloader\mloader_downloads\--capture-api\viewer/10000001"

            _                 _
  _ __ ___ | | ___   __ _  __| | ___ _ __
 | '_ ` _ \| |/ _ \ / _` |/ _` |/ _ \ '__|
 | | | | | | | (_) | (_| | (_| |  __/ |
 |_| |_| |_|_|\___/ \__,_|\__,_|\___|_|


27.02.2026 18:21:09 |   INFO   |    main.py     396  | Started export
Error: Download request failed: MangaPlus API returned no manga_viewer payload.

(.venv) C:\Users\WDAGUtilityAccount\Desktop\mloader>

mloader_downloads.zip

Here's a .zip with my results from my attempts—they're about the same as the other day ( There are issues connecting to Manga+. Please try again later. )

[l0westbob]

ok since you are using a for loop in a windows powershell, i am not sure whats going on. Could you please just execute one command like:

mloader --title 100011
or
mloader https://mangaplus.shueisha.co.jp/titles/100011

And verify that single download without your for loop is working?

Also please open up an issue in my fork repository, thanks

[l0westbob]

@KodywithaK
Your logs suggest the API call itself is succeeding at HTTP level, but MangaPlus is returning an error envelope (no usable success.title_detail_view / success.manga_viewer payload). A common cause on Windows is environment values being injected unexpectedly.

Could you check what auth-related envs are active in your PowerShell session?

Get-ChildItem Env:APP_VER,Env:OS,Env:OS_VER,Env:SECRET

It should match the values you find in the compose.yaml file. If they don't, then most likely windows injected the OS env-variable with Windows_NT (or similar), which does not work with mloader.

Since i dont know if this is a problem or not, i will still add a safeguard that prints an error if you start mloader with an unsupported OS.

[KodywithaK]

@l0westbob I ran Get-ChildItem Env:APP_VER,Env:OS,Env:OS_VER,Env:SECRET and it showed exactly as you expected: OS=Windows_NT and the other env-variables were undefined

Command Prompt Output

(.venv) C:\Users\WDAGUtilityAccount\Desktop\mloader>powershell -Command " Get-ChildItem Env:APP_VER,Env:OS,Env:OS_VER,Env:SECRET "
Get-ChildItem : Cannot find path 'APP_VER' because it does not exist.
At line:1 char:2
+  Get-ChildItem Env:APP_VER,Env:OS,Env:OS_VER,Env:SECRET
+  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (APP_VER:String) [Get-ChildItem], ItemNotFoundException
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.GetChildItemCommand


Name                           Value
----                           -----
OS                             Windows_NT
Get-ChildItem : Cannot find path 'OS_VER' because it does not exist.
At line:1 char:2
+  Get-ChildItem Env:APP_VER,Env:OS,Env:OS_VER,Env:SECRET
+  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (OS_VER:String) [Get-ChildItem], ItemNotFoundException
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.GetChildItemCommand

Get-ChildItem : Cannot find path 'SECRET' because it does not exist.
At line:1 char:2
+  Get-ChildItem Env:APP_VER,Env:OS,Env:OS_VER,Env:SECRET
+  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : ObjectNotFound: (SECRET:String) [Get-ChildItem], ItemNotFoundException
    + FullyQualifiedErrorId : PathNotFound,Microsoft.PowerShell.Commands.GetChildItemCommand

So I then manually set the variables, ran mloader and it turned out perfectly !

(.venv) C:\Users\WDAGUtilityAccount\Desktop\mloader>set "APP_VER=97" & set "OS=ios" & set "OS_VER=18.1" & set "SECRET=<YOUR_SECRET_HERE>" & mloader https://mangaplus.shueisha.co.jp/viewer/1000762

Command Prompt Output

            _                 _
  _ __ ___ | | ___   __ _  __| | ___ _ __
 | '_ ` _ \| |/ _ \ / _` |/ _` |/ _ \ '__|
 | | | | | | | (_) | (_| | (_| |  __/ |
 |_| |_| |_|_|\___/ \__,_|\__,_|\___|_|


28.02.2026 19:25:25 |   INFO   |    main.py     405  | Started export
28.02.2026 19:25:26 |   INFO   | downloader.py  140  | 1/1) Manga: Dragon Ball
28.02.2026 19:25:26 |   INFO   | downloader.py  141  |     Author: Akira Toriyama
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: Tale 4: They Call Him… the Turtle Hermit!
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: Tale 10: Onward to Fry-Pan…
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: Tale 19: At Last… the Dragon!
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: Tale 67: Go West, Young Goku…
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: Tale 186: Panic at the Tenka'ichi Budôkai!
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:06 Nothing Up My Sleeve…
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:10 The Needs of the Many…
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:18 Closer...Closer…
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:21 One Down…
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:32 The Mystery of the Kaiō-ken
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:77 The Enemy of My Enemy…
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:88 With Allies Like These…
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:112 Son Goku… Resurrected!!
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:148 One Down…
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:156 #17,#18…#16?
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:176 New Piccolo… Last Piccolo?
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:242 Hercule’s Courage!
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:246 Shin’s Surprise
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:247 Videl… Battered
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:257 Yakon’s Treat
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:263 Vegeta’s Pride
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:272 The Mastermind’s Demise
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:276 Bobbidi’s Revenge!!
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:282 Goku’s Time
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:287 The Earth’s Secret Weapon!
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:293 Humanity’s End
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:303 Gohan’s Counterattack!
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:304 What’s Boo Doing?!
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:311 Vegerot’s Game
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:319 Vegeta’s Plan
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:322 Battle’s End
28.02.2026 19:25:26 | WARNING  | downloader.py  390  |     Encoding fix skipped for: DBZ:323 A Happy Ending… And Then…
28.02.2026 19:25:26 |   INFO   | downloader.py  324  |     Found 0 existing chapter files in 'mloader_downloads\Dragon Ball'.
28.02.2026 19:25:26 |   INFO   | downloader.py  174  |     1 chapter(s) to download for 'Dragon Ball'.
28.02.2026 19:25:26 |   INFO   | downloader.py  224  |     1/1) Chapter #001: Tale 1 Bloomers and the Monkey King
#001  [####################################]  30/30
Download summary: downloaded=1, skipped_manifest=0, failed=0
28.02.2026 19:25:34 |   INFO   |    main.py     443  | SUCCESS

(.venv) C:\Users\WDAGUtilityAccount\Desktop\mloader>

Thanks again for updating mloader on your end, and helping me troubleshoot !!