Calibre cannot open ebook reader, edit books, or re-open once closed

[baggins41]

I've recently run into a rather odd set of symptoms with Calibre and I was wondering if anyone else had encountered anything similar. For context, I am running Windows 10 64-bit and I do not use any always-on third-party security software.

The problem is I cannot seem to do anything in Calibre that would open a new (non-dialog) window. That is to say, I can open up settings, run plug-ins, or tweak metadata just fine, but when I try to view an e-book with the built-in reader or open up the book editor, nothing happens. The "busy" cursor spins for a moment and then it goes back to normal with no result.

On top of that, if I close Calibre, I am unable to re-open the program again unless I first log off my Windows user account and then log back in. The process shows as running in the Task Manager, but no window displays. Killing the task and then attempting to re-open it also makes no difference.

At the same time this started happening, I was no longer able to complete ePUB -> MOBI conversions of any books. Though, conversions had been getting more and more likely to "stick" at 67% for the past couple months, so that may be a separate issue. (I would wait 15 minutes for a book to convert, it would appear to have gotten stuck, I would cancel the job and then initiate conversion again and it would complete in less than a minute the second time.)

If, on a fresh login, I browse to an epub file and double-click it, it opens up in Calibre's viewer just fine, but then I am unable to open the main Calibre program after doing so.

I tried completely removing all traces of Calibre 2.51.0 from my computer, using Add/Remove Programs and then deleting any leftover registry settings in both HKLM and HKCU, completely deleting my library from my documents folder and all calibre directories from Users\AppData, and rebooted.

I then tried installing version 2.48.0 and found that it exhibited the exact same same symptoms even in the clean environment. Finally, I wiped everything clean once again and tried installing version 1.48.0 in case it was a Qt 5 issue. Viola, everything now works properly again! I copied my old library, plugins and settings folders back into place and everything works just fine under the old version.

I have not, to my knowledge, installed any new software other than Windows updates before this started happening.

For now I am fine running 1.48.0, but if anyone has any thoughts on potential resolutions for the problem I'd love to hear them. Or if others have the same problem and it's not just a weird glitch solely on my computer, I'd be happy to assist in tracking it down with providing any log files or running any tests requested.

[BetterRed]

Crikey! What type of CPU are you running!

Perhaps you could install (if necessary) something like Piriforms Speccy and post a screen shot of what it displays for the CPU. IIRC lack of support for the SS3 instruction set was the Qt5 'gotcha'.

BR

[theducks]

Have you ever had a second monitor attached?
or reduced your screen resolution SETTING a quite a bit?

Both could put the dialog off-screen

[baggins41]

Originally Posted by BetterRed

IIRC lack of support for the SS3 instruction set was the Qt5 'gotcha'.

It's definitely not an SSE3 issue (edit: unless Microsoft just broke something in that area, but that seems far-fetched). I've been running the 2.x series of Calibre on this same hardware for well over a year with no issues. Still, here are the CPU specs:

Originally Posted by theducks

Have you ever had a second monitor attached?
or reduced your screen resolution SETTING a quite a bit?

Both could put the dialog off-screen

Yeah, that was one of my first thoughts- I run dual monitors and have run into that sort of siutuation with other programs, but in this case I don't think that's what's going on. For one thing, I have not changed the monitor placement nor the screen resolution recently.

It's also been my experience that even when a window gets displayed off-screen, you can often get it back with the Alt-Space->Move shortcut and the arrow keys. In this case, the main Calibre window never appears to lose focus and alt-space doesn't bring up the system menu on any "hidden" windows, so I'm pretty sure that's not what's happening here.

[kovidgoyal]

That sounds like something on your machine is blocking calibre from launching worker processes. Worker processes are used to run conversions, open the viewer/editor, etc. The usual suspect in such cases is an antivirus program, but you say you aren't running one.

[eschwartz]

Originally Posted by BetterRed

Crikey! What type of CPU are you running!

Perhaps you could install (if necessary) something like Piriforms Speccy and post a screen shot of what it displays for the CPU. IIRC lack of support for the SS3 instruction set was the Qt5 'gotcha'.

BR

SSE2 was the gotcha. Any Intel CPU produced after 2001 (or AMD after 2003) should be capable of it -- and SSE2 is a requirement to install Windows 8.

(And technically, SSE2 is just commonly missing on WinXP, but Qt5 doesn't support XP for other reasons too. In fact, you can custom-build Qt5 without SSE2 although it runs slower.)

...

@baggins41,

As the master said, this problem usually indicates an overzealous antivirus. But I suppose a more definite way to find out would be to run calibre in debug mode. On the command line, type:

calibre-debug -g

Then try to open a book in the viewer/editor.

Hopefully a useful error message will show up.

[BetterRed]

@baggins41 - also try running 2.51 in Safe Mode.

Also check that you're not using any of the packages mentioned in calibre freezes/crashes occasionally?.

Might also be worth while installing and trying calibre portable v 2.51

BR

[baggins41]

Originally Posted by eschwartz

As the master said, this problem usually indicates an overzealous antivirus. But I suppose a more definite way to find out would be to run calibre in debug mode. On the command line, type:

calibre-debug -g

Then try to open a book in the viewer/editor.

Hopefully a useful error message will show up.

I suppose I should have posted my output from that at the beginning. Here is the output I got from calibre-debug upon opening the program and then attempting the "Edit Book" command:

calibre 2.50.1  isfrozen: True is64bit: False
Windows-8-6.2.9200 Windows ('32bit', 'WindowsPE')
32bit process running on 64bit windows
('Windows', '8', '6.2.9200')
Python 2.7.9
Windows: ('8', '6.2.9200', '', 'Multiprocessor Free')
Successfully initialized third party plugins:
Qt: Untested Windows version 10.0 detected!
Unable to set queue size on tablet. The tablet will not work.
Starting up...
Started up in 3.64 seconds with 1508 books
Worker Launch took: 0.144999980927

Wasn't much help I'm afraid. Subsequent launches would simply hang after the "Qt: Untested Windows version 10.0 detected!" message (which is what inspired me to try the version with the earlier Qt library.


Fortunately, after much random testing (shutting down Windows Defender and SmartScreen filter, killing non-critical processes, and shutting down completely unrelated services), I've finally managed to narrow down the problem to one specific Windows service: WTabletServiceCon a.k.a. "Wacom Consumer Service". If I kill it, everything works great. If I restart it, all the problems come back.

I have no idea why Calibre is being affected or why this is suddenly acting up now (I've been using my current Wacom tablet with this system for a couple of months), but no one ever accused Wacom of making great drivers.

Thanks for the tips guys. Hopefully this thread will be helpful to someone else if they get bitten by this in future.

[eschwartz]

As the FAQ entry BetterRed linked to says, Wacom devices are known to cause problems with Qt5, although I would've expected the issue to show up whenever running calibre at all -- not just when launching secondary components from the main application.

[BetterRed]

ninja'd

As I said

Originally Posted by BetterRed

Also check that you're not using any of the packages mentioned in calibre freezes/crashes occasionally?.

In there you'll find this

There are several possible things I know of, that can cause this:
...

• You are using a Wacom branded USB mouse. There is an incompatibility between Wacom mice and the graphics toolkit calibre uses. Try using a non-Wacom mouse.

...

I'm surprised you've gotten away with using the Wacom Tablet at all, they've been a 'known problem' for calibre (Qt I think) for quite some time. Although i note the tablet specifically is no longer mentioned in the FAQ only the mouse.

BR

[eschwartz]

Well, there is this: https://github.com/kovidgoyal/calibr...07de5ab0a813f5

So tablets are mentioned now (again?) -- I guess it was an oversight or inaccurate wording.

[baggins41]

Originally Posted by BetterRed

I'm surprised you've gotten away with using the Wacom Tablet at all, they've been a 'known problem' for calibre (Qt I think) for quite some time. Although i note the tablet specifically is no longer mentioned in the FAQ only the mouse.

For the record, I didn't see your last response because you posted it while I was replying with my own, but yeah, perhaps that FAQ entry should be broadened a bit. This is definitely not a mouse (though I wouldn't be shocked to learn the drivers share a lot of the same code) and it also didn't manifest as an "occasional" freeze or crash.

I don't know what to tell you as far as how I've "gotten away with it" for this long. I've been using Wacom drawing tablets for a couple of years now on this same computer and I haven't seen any problems up 'till now. The conversion issue I mentioned may very well have started around the same time I upgraded from a Wacom Bamboo to an Intuos a couple of months ago, but conversions shouldn't have anything to do with the Qt library, would they?

The other issues only just started last week and AFAIK, the Wacom drivers don't do any kind of auto-update and there's nothing in my Windows Update history to indicate Windows 10 pushed through any Wacom drivers, so I'm at a complete loss to explain the sudden change.

[eschwartz]

We sure do a lot of simultaneous posting in this thread.

The gap is tightening....

[BetterRed]

@baggins41 - maybe Kovid can say why the Wacom drivers would effect conversions, and why you've gotten away with it them for so long etc, its beyond my ken and paygrade.

No worries with the cross posting. happens all the time - adds to the fun.

BR

[kovidgoyal]

conversions use Qt (for rendering svg images, among other things). As for why your problems are likely to only start recently, I haven't the foggiest.