Fix qBittorrent V2 auth check breaking against qBit 5.2.0+ (empty 204 response)

[benhumphry]

Problem

qBittorrent 5.2.0 changed POST /api/v2/auth/login to return HTTP 204 No Content with an empty body on successful authentication. Before 5.2.0 the endpoint returned HTTP 200 with body "Ok.".

The auth check in QBittorrentProxyV2.AuthenticateClient is:

// returns "Fails." on bad login
if (response.Content != "Ok.")
{
    _logger.Debug("qbitTorrent authentication failed.");
    throw new DownloadClientAuthenticationException("Failed to authenticate with qBittorrent.");
}

An empty 204 body is not "Ok.", so this throws DownloadClientAuthenticationException against any qBittorrent 5.2.0+ even when the login actually succeeded. The download client shows as "Failed to authenticate with qBittorrent" in Bookshelf and stops working.

The change is observable directly:

$ curl -i -X POST -d 'username=admin&password=...' http://qbit:8080/api/v2/auth/login
HTTP/1.1 204 No Content
Set-Cookie: SID=...; HttpOnly; SameSite=Strict

(Pre-5.2.0 the same call returned HTTP/1.1 200 OK and body Ok..)

The qBit 5.2.0 release-notes line that documents this is WEBAPI: Send 204 when WebAPI response contains no data (qbittorrent/qBittorrent#21472, shipped in 5.2.0).

Fix

Add a IsNotNullOrWhiteSpace() guard so an empty body short-circuits the failure branch — only treat the response as failed if it has content AND that content is not "Ok.":

// returns "Fails." on bad login; qBit 5.2.0+ returns empty 204 on success
if (response.Content.IsNotNullOrWhiteSpace() && response.Content != "Ok.")
{
    _logger.Debug("qbitTorrent authentication failed.");
    throw new DownloadClientAuthenticationException("Failed to authenticate with qBittorrent.");
}

IsNotNullOrWhiteSpace() is already in scope via the existing using NzbDrone.Common.Extensions; import — no new dependencies.

Why this is the right shape

The same one-line guard already lives in all the other Servarr forks that share the qBit V2 proxy:

Project	Status	File
Sonarr	Has the guard	QBittorrentProxyV2.cs
Radarr	Has the guard	(mirror of Sonarr)
Lidarr	Has the guard	(mirror of Sonarr)
Bookshelf	Missing the guard — this PR	—

The behaviour difference is exactly why Sonarr/Radarr/Lidarr keep working against qBit 5.2.0 while Bookshelf does not. This change brings Bookshelf into line.

Risk

Negligible. The guard only changes behaviour when response.Content is null or whitespace, which previously was always classified as "auth failed" and now is classified as "auth ok". Real failures still return either a non-2xx HTTP status (handled by the catch (HttpException) block above) or body "Fails." (still caught by the != "Ok." half of the new condition).

Test plan

• Connect Bookshelf to qBittorrent 5.1.x (200 + "Ok."): auth still succeeds. ✅
• Connect Bookshelf to qBittorrent 5.2.0+ (204 + empty body): auth now succeeds. ✅ (was failing pre-patch)
• Connect Bookshelf with wrong password to either qBit version (200 + "Fails."): auth still throws DownloadClientAuthenticationException. ✅

Verified locally by rebuilding Readarr.Core.dll from a patched develop checkout (commit c21c4134…) and dropping it into the upstream ghcr.io/pennydreadful/bookshelf:hardcover image. Test Connection in Settings → Download Clients flips from red to green.

[AlvaroEstradaDev]

I made a local build with this fix for myself, I can verify that it works.

[Florentina72]

I request that the creators of Bookshelf fix this within Bookshelf itself. The above kind of solutions are Greek and Latin for us commoners.

[GinSoakedBoy]

I request that the creators of Bookshelf fix this within Bookshelf itself. The above kind of solutions are Greek and Latin for us commoners.

+1 for this. I see this thread referenced as a 'fixed' issue, but I don't see a fix.

[EggEnormous]

I would also dearly love for this to be incorporated into Bookshelf.

[ozhound]

Also confirming this PR works and i can connect to qbit now.

[ReaVNaiL]

We'll need to wait for one of the maintainers to merge it unfortunately. The fix works.

[Adiar1]

I'm waiting for it as well. Just dropping a comment to show demand

[manalshaikh]

any update? without this, its completely borked and wouldn't work. im setting up a new instance of bookshelf(for the first time ever) and cant seem to get it to work. this is kinda breaking.

[SolomonIxanSmith]

Also commenting to try and show demand.

[Roskott]

Also bumping to show desire

[Brodieman]

Just trying to add Bookshelf as an app and running into this. I do not see a word on an official fix. Anyone have step by step on fixing this manually? The code to fix it on top, I see that, but I do not see a file or where to put it. If someone has something or could write up something people could follow to correct this until Bookshelf does, we would apricate it.

[EFH52]

Curious as to whether there is life here or that we count things a dead and move on to other projects. I spent a couple hours working this issue yesterday before finding this issue and the attendant PR.

[GinSoakedBoy]

Are there any other forks of Readarr out there?

Chaptarr is still in alpha, but the public beta should be coming soon.

[Brodieman]

If this is never fixed, I get it. These projects are a lot of time. I am just hoping someone can write something up for people to follow along to correct this.

I think most of us that use stuff like think are not programmers but have good IT knowledge to follow along. Programmers can figure this out, people with IT knowledge might not be able to.

[SolomonIxanSmith]

If this is never fixed, I get it. These projects are a lot of time. I am just hoping someone can write something up for people to follow along to correct this.

I think most of us that use stuff like think are not programmers but have good IT knowledge to follow along. Programmers can figure this out, people with IT knowledge might not be able to.

What I did, and others probably have done, is fork the project and merge the pull request and then point docker to your image. It doesn't require any coding or anything other than using the github website. I'd recommend asking your AI tool of choice to help you with the steps.

[EggEnormous]

I found a project called Bindery which is adding features and fixing bugs very actively. I'm still messing with it since I'm on vacation, but it looks promising.

…

On Thu, Jun 4, 2026, 10:40 AM SolomonIxanSmith ***@***.***> wrote: *SolomonIxanSmith* left a comment (pennydreadful/bookshelf#158) <#158 (comment)> If this is never fixed, I get it. These projects are a lot of time. I am just hoping someone can write something up for people to follow along to correct this. I think most of us that use stuff like think are not programmers but have good IT knowledge to follow along. Programmers can figure this out, people with IT knowledge might not be able to. What I did, and others probably have done, is fork the project and merge the pull request and then point docker to your image. It doesn't require any coding or anything other than using the github website. I'd recommend asking your AI tool of choice to help you with the steps. — Reply to this email directly, view it on GitHub <#158?email_source=notifications&email_token=AWJUYUWIEXMWB4QYPEHDYHD46GYALA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINRSGQ3DQMZSGY2KM4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLDGN5XXIZLSL5RWY2LDNM#issuecomment-4624683264>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AWJUYUVPRG2ZIBD2DTKY33L46GYALAVCNFSM6AAAAACYVGTNXCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHM2DMMRUGY4DGMRWGQ> . Triage notifications, keep track of coding agent tasks and review pull requests on the go with GitHub Mobile for iOS <https://github.com/notifications/mobile/ios/AWJUYURMOT365INDXQ6R3N346GYALA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINRSGQ3DQMZSGY2KM4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJKTGN5XXIZLSL5UW64Y> and Android <https://github.com/notifications/mobile/android/AWJUYUV3KIWMY66PKH6JMZL46GYALA5CNFSNUABFM5UWIORPF5TWS5BNNB2WEL2JONZXKZKDN5WW2ZLOOQXTINRSGQ3DQMZSGY2KM4TFMFZW63VHMNXW23LFNZ2KKZLWMVXHJLTGN5XXIZLSL5QW4ZDSN5UWI>. Download it today! You are receiving this because you commented.Message ID: ***@***.***>

[Brodieman]

If this is never fixed, I get it. These projects are a lot of time. I am just hoping someone can write something up for people to follow along to correct this.
I think most of us that use stuff like think are not programmers but have good IT knowledge to follow along. Programmers can figure this out, people with IT knowledge might not be able to.

What I did, and others probably have done, is fork the project and merge the pull request and then point docker to your image. It doesn't require any coding or anything other than using the github website. I'd recommend asking your AI tool of choice to help you with the steps.

I use TrueNAS, not a standard Docker image, so that would not work for me.. However, I have been in IT for 20 years but never in coding. When you talk about forking and stuff, I have no clue what that means or how to accomplish it. I was hoping for a "this file is located here, change this code to this". That I can do. Thanks for the reply

[AlvaroEstradaDev]

I made a fork and a build of this fix, everyone is free to use it until an official update is done.
The only change I did was for the CI to be able to build it, but I invite everyone to check the code before installing.
ghcr.io/alvaroestradadev/bookshelf:hardcover

[EggEnormous]

I made a fork and a build of this fix, everyone is free to use it until an official update is done. The only change I did was for the CI to be able to build it, but I invite everyone to check the code before installing. ghcr.io/alvaroestradadev/bookshelf:hardcover

You're my hero!

[Adiar1]

I made a fork and a build of this fix, everyone is free to use it until an official update is done. The only change I did was for the CI to be able to build it, but I invite everyone to check the code before installing. ghcr.io/alvaroestradadev/bookshelf:hardcover

Yeah that's what I ended up doing too.

[GinSoakedBoy]

I made a fork and a build of this fix, everyone is free to use it until an official update is done. The only change I did was for the CI to be able to build it, but I invite everyone to check the code before installing. ghcr.io/alvaroestradadev/bookshelf:hardcover

Would you be willing to apply the fix to the softcover (Goodreads) version of Readarr?

[AlvaroEstradaDev]

I made a fork and a build of this fix, everyone is free to use it until an official update is done. The only change I did was for the CI to be able to build it, but I invite everyone to check the code before installing. ghcr.io/alvaroestradadev/bookshelf:hardcover

Would you be willing to apply the fix to the softcover (Goodreads) version of Readarr?

It got build at the same time, sorry if that wasn't clear.
ghcr.io/alvaroestradadev/bookshelf:softcover

[GinSoakedBoy]

I made a fork and a build of this fix, everyone is free to use it until an official update is done. The only change I did was for the CI to be able to build it, but I invite everyone to check the code before installing. ghcr.io/alvaroestradadev/bookshelf:hardcover

Would you be willing to apply the fix to the softcover (Goodreads) version of Readarr?

It got build at the same time, sorry if that wasn't clear. ghcr.io/alvaroestradadev/bookshelf:softcover

Derp, thank you!

[andrewmuhn]

👍

[Roskott]

So, what's preventing the build for this? I see @ReaVNaiL approved, but we're waiting for... @ReaVNaiL to approve? is it just a double tap issue?

[klein1jo]

@Roskott penny would have to merge and penny has gone MIA. I've created a fork that merges all of bookshelf's open pull requests including a fix for Qbittorrent 5.2.x. You can use it if you want. https://github.com/klein1jo/bookshelf

[Kazwahs]

On Truenas Scale I converted Bookshelf to a custom app and changed the image to the hardcover one from @klein1jo, https://github.com/klein1jo/bookshelf. Worked great, back up and running with Qbit.

[joel35]

Waiting for this fix. Any update? Seems like it should be good-to-go.

[pennydreadful]

sorry i use an older qbit so don't have this problem

fixed in #170

if you'd like to help contribute i would be glad to add maintainers!