You need to find out what is using the 8181 port on your system and then maybe change that port to something else.

21 hours ago, ByteHeaven said:

Ok, after last update "Error: This application requires a secure connection (HTTPS). Please check the URL."

Tryed to change webui to 8181 but Unraid tells it is in use? (does not accept it and start calibre with that?)

So? How to fix?? AND WHY? If I have local calibre in my home network WHY are we forced to use HTTPS?

I agree. No reason to have HTTPS here. I worked around it by adding my Calibre container to Tailscale and accessing it via that.

Make sure you add port 8181 in your docker template for HTTPS to start working/be accessible

21 hours ago, ByteHeaven said:

Ok, after last update "Error: This application requires a secure connection (HTTPS). Please check the URL."

Tryed to change webui to 8181 but Unraid tells it is in use? (does not accept it and start calibre with that?)

So? How to fix?? AND WHY? If I have local calibre in my home network WHY are we forced to use HTTPS?

Make sure you add port 8181 in your docker template for HTTPS to start working/be accessible

I added port 8181, but I'm still getting the same error.

"Error: This application requires a secure connection (HTTPS). Please check the URL."

You added port 8181 in the Unraid template and then went to https://IP:8181 and it was still an issue?

You can update your webURL in the template as well to reflect HTTPS and port 8181

With the help of a friend I realized the webui shortcut doesn't work properly. Yes, when using https://serverip:8181, it works. I'll look into changing the webURL. Thanks.

3 minutes ago, Groovy said:

With the help of a friend I realized the webui shortcut doesn't work properly. Yes, when using https://serverip:8181, it works. I'll look into changing the webURL. Thanks.

Ensure the update container page is set to advanced view (upper right corner).

Ok this starts to be really annoying.. really nice work from developers of calibre to break the *** up for bunch of people, who are NOT developers..

I managed? to change port but now it tells it cannot make secure connection?? Thus? What should I do? And the port conflicts with tautulli.. which use 8181 and haven't figured out how to get it working with any other port.. so they fracked up entire media server with that forced change..

So now I have error: ERR_SSL_PROTOCOL_ERROR

And how can I fix that?

Anyone have any actually working alternative for ebooks for calibre on server? Which does not have bunch of *** as developers?

Edited August 4, 2025Aug 4 by ByteHeaven

And after figuring out 2 hours of wasted time... typical open source project again, where devs do not care at all about users...

First: Update was fracked up, because it DID not do it correctly as it did not get working anyway... only way was (after figuring out to get tautulli to another port) was to completely wipe up settings (thanks a lot... so settings are now fracked up..) and install it completely as new... now it works... but a second I figure out something which works just barely enough I switch and abandon calibre...

Can someone please post screenshots of correct configuration after the required changes? I'm also getting the infamous "ror: This application requires a secure connection (HTTPS). Please check the URL." error message and can't figure out where should I replace the port by 8181...

13 hours ago, jul9000 said:

Can someone please post screenshots of correct configuration after the required changes? I'm also getting the infamous "ror: This application requires a secure connection (HTTPS). Please check the URL." error message and can't figure out where should I replace the port by 8181...

Ok step by step how I got it working after struggling 2 hours...

1: Uninstalled old calibre (it did NOT update so new required settings are there as I did NOT have https configured to be used.. the pem file was in folder but it did not use it or it was not working or something. So complete removal of old version) -edit- and of course if you are smarter than I was.. take screenshot first from all path settings you have to let calibre access your storage and make it for new setup exactly same way (that way when you replace old settings to new one it should straight away work just as before without fixing paths first as I did not remember mount points I had put paths on olden so made new ones and they were not same as old so calibre first wanted to get paths to books and had to fix also path to auto import...)

btw: if any admin for docker devs read this: there is kinda of really stupid "feature" in the setting the paths. When it starts to reconfigure it will USE faulty path, die, and whole calibre docker disappear to orphans... just forgot to put / to first which of course is error but hey, maybe when applying it should refuse and tell there is error and not kill itself completely... one extra install again there for me when figuring this out without any decent instructions how to fix this mess and apologies maybe a bit angry comments before, I was rally pissed of and frustrated with this approach "let's kill this for everyone who do not understand everything under the hood completely" which is really a common sin for open source devs and how they approach things.. seems for you too.. and seriously main reason WHY these kind of systems never hit main stream.. because devs do not care to think how to make things simple and easy without understanding everything there).

added with take out settings folder in app share (advice: rename old calibre folder to calibre-old) so it installs completely clean new one (if you have settings there it does not add required fields to settings, you probably could(?) add them manually and it would work(?) to existing one but at least for me, if I tried to replace app folder with old one after install, calibre just crash on start with error, thus something on old folders is conflicting with new version... HOWEVER in config folder there I replaced calibre folder with old config calibre folder and all my settings were saved, so at end did not loose all the fine-tuning done for my calibre setup)

Then depending on if you need to fine-tune something (or try to get it working without cleaning whole system) in calibre docker settings remember advanced view



And then you should have paths this way



These are default settings for clean setup (I did NOT have without clean setup that last https port setting in settings at all.. thus.. update did NOT add that even when it is now required.. you probably can add that manually(?) did not try that



One problem I had is that Unraid IS media server for me, so there is bunch of media related dockers. And Tautulli is conflicting with that port 8181. After tinkering figured out how to get it working (no I am not in-depth linux native understanding dockers etc. One reason why I have Unraid and ready made dockers in there.. I don't have to be... in these forums I find it sometimes very annoying when all instructions are on the level "hey do just this and this" with expectation everyone is just as natively swimming on linux console and understanding completely how docker works etc...)


So Tautulli settings for avoiding conflict if you use Tautulli (with advanced view of course again). Now my Tautulli opens with port 8182 and is not conflicting with calibre...

Edited August 6, 2025Aug 6 by ByteHeaven

If you don't care about the update you can always roll back to 8.6 by changing the repository, like this:

The old message about https was cached for me so I had to CTRL+F5 to load Calibre in the browser.

I actually found that if I just put in https://your ip address:8181 into your browser, your calibre should open. The issue is that you can't use the WebUI from the docker because it is set to use the http://ip address:8080. You need to type in the correct address into the web browser yourself.

I do have another issue though. When I am in the WebUI in chrome and I try to click on a URL link such as a "plugin homepage" link in a plugin, nothing happens. It doesn't go anywhere. I tried adjusting the tweak "change the programs that are run when opeing files/URLs" but it isn't working when I set it like this openers_by_scheme = {'http*': 'Google Chrome.lnk %u'}. I am assuming that it is because this is running through a docker on unraid. How do I get these links to open a web browser page?

I actually found that if I just put in https://your ip address:8181 into your browser, your calibre should open. The issue is that you can't use the WebUI from the docker because it is set to use the http://ip address:8080. You need to type in the correct address into the web browser yourself.

You can change the port used in the webui link.

Be sure view is set to advanced.

Edited August 7, 2025Aug 7 by wgstarks
typo

On 8/6/2025 at 12:45 PM, Hogwind said:

If you don't care about the update you can always roll back to 8.6 by changing the repository, like this:

The old message about https was cached for me so I had to CTRL+F5 to load Calibre in the browser.

thank you so much for the tip with the "hard reload"... I really thought the linuxserver guys went back and did that to all the old images as well, but the site had just cached ;-)

On 8/6/2025 at 11:45 AM, Hogwind said:

If you don't care about the update you can always roll back to 8.6 by changing the repository, like this:

The old message about https was cached for me so I had to CTRL+F5 to load Calibre in the browser.

Thanks so much! That did it for me. I am not exposing the Calibre UI to the web anyway, so I don't NEED https. (I do expose Calibre Web, but that's a different docker)

On 8/8/2025 at 12:08 AM, wgstarks said:

You can change the port used in the webui link.

Be sure view is set to advanced.

Nope. I tried manually typing it in the browser, but it didn't work for me. Neither on Firefox or Chrome.

n.b.: I ended up reverting to linuxserver/calibre:8.6.0 as repository and that fixed it for me

This has been a nightmare, isn't there just an option to NOT use SSL? Everything is internal I don't need an SSL link and nothing I do works.

I have to admit that since I access unraid through tailscale and bumped into this issue I downgraded to 8.6.0 as well. Hopefully it will be resolved in the future so that http is once again allowed. I'll check back periodically but am happy to report that 8.6.0 still works fine.

Edited August 17, 2025Aug 17 by ducato

Also rolled back to 8.6.0. Looking forward to a fix to the https problem

Can somebody tell me why this is happening: every time I update calibre, it rolls back my settings. I must go back and point it to the library, restart the content server, go back to share over web and click to start content server whenever calibre starts. Why????

Thanks

Ok this starts to be ridiculous. Not sure what you decided to break this time, but when starting calibre CPU goes to 100%, and it never starts, no errors anything in log... going back to linuxserver/calibre:8.6.0 and hoping to find alternative for this, because seems project is going very bad direction lately...

4 hours ago, ByteHeaven said:

Not sure what you decided to break this time

Who is “you”? The other users in this forum?

If you want to contact the devs you should probably post issues on GitHub.

Gotta pay the Open Source Tax again. Random changes that do not help me and cause me more work at the same time. So irritating that they make these decisions so casually without need to justify it. I really want to love open source software, but I can only tolerate it in reality. The lack of accountability to the user makes it impossible to love. I wish there was another way to do it, it is either big tech abuse or this crap. I pay these devs monthly and they call it a donation instead of a customer transaction. Not sure I like that at all.

The software ecosystem needs a different model. I use so much software daily in my business and my personal life and it is like being in multiple abusive relationships at once. Sorry to rant, don't mind me.