Upgrade W10 64bit

quoddle · 07-22-2022, 07:32 AM

Hi,
I've been trying to upgrade to Calibre 6.1 on a 64bit W10 pc running Windows Defender. It installs normally but when I run it I get "This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: direct2d, minimal, offscreen, Windows"

I've tried reinstalling several times with the same result. I've had to uninstall and go back to 5.44 which woks fine.

Anything I can do to get the new version working?

JSWolf · 07-22-2022, 08:43 AM

Quote:

Originally Posted by quoddle

Hi,
I've been trying to upgrade to Calibre 6.1 on a 64bit W10 pc running Windows Defender. It installs normally but when I run it I get "This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
Available platform plugins are: direct2d, minimal, offscreen, Windows"

I've tried reinstalling several times with the same result. I've had to uninstall and go back to 5.44 which woks fine.

Anything I can do to get the new version working?

Try installing 6.1 again and then rebooting into safe mode. If that site won't work, try a repair install while in safe mode.

BetterRed · 07-22-2022, 09:04 AM

Moderator Notice

Moved from the Issues after updating to calibre 6.1 64 bits thread.

BR

quoddle · 07-22-2022, 09:54 AM

Tried that but the same error in Safe Mode.
Startup Repair went through the Diagnosing your PC stage then came up with Startup Repair couldn't repair your PC.
Everything else works fine it's just the new version of Calibre that won't run.

georgemk · 07-22-2022, 10:40 AM

@quoddle

Looking on the internet for that error message, it seems that this error occurs where you have 2 or more programs each with their own version of the QT software (which Calibre uses too) and the interactions between them. Basically 1 program finds the wrong QT files at runtime (an incompatible version) and the result is this message.

Have a look in your "System Environment Variables" for any variable name starting with QT and if found see what software uses it. That is one possible cause as it would divert Calibre from loading its QT files and try to load another program's version.

Don't just delete any such variable you find but investigate as you could stop something else working - you'd be surprised at how many programs use QT behind the scenes.

quoddle · 07-22-2022, 10:56 AM

It's not listed there at all. Do I need to manually install it?

kovidgoyal · 07-22-2022, 11:10 AM

That's the error you get trying to run calibre 6 on windows 8. Are you sure you are on windows 10?

quoddle · 07-22-2022, 11:12 AM

Yes, Windows 10 Pro though an old version

JSWolf · 07-22-2022, 11:41 AM

Quote:

Originally Posted by quoddle

Yes, Windows 10 Pro though an old version

I suggest you update your Windows 10 to the latest version.

georgemk · 07-22-2022, 11:50 AM

Quote:

Originally Posted by quoddle

It's not listed there at all. Do I need to manually install it?

No, I'm just going from the other forums where people have had the QT system variables misdirecting products. Calibre has everything it needs within its installer package so doesn't need anything else.
It was a possible cause of your issue not the only one unfortunately.

JSWolf · 07-22-2022, 05:32 PM

I'm taking a guess that maybe Qt6 is not compatible with older versions of Windows 10.

quoddle · 07-22-2022, 05:36 PM

That's what it looks like. Unfortunately my copy of Windows was modified several years ago by my son in law to stop it updating as the updates were causing more problems than they solved. It's been fine ever since until this problem with Calibre.
The only way I can update is a clean install which I don't want to do as it'll take me forever to reinstall everything.
Looks like I'm stuck with v5.44

JSWolf · 07-22-2022, 06:24 PM

Quote:

Originally Posted by quoddle

That's what it looks like. Unfortunately my copy of Windows was modified several years ago by my son in law to stop it updating as the updates were causing more problems than they solved. It's been fine ever since until this problem with Calibre.
The only way I can update is a clean install which I don't want to do as it'll take me forever to reinstall everything.
Looks like I'm stuck with v5.44

If he turned off the update services, turn them back on. And you could ask your son what he did and get him to undo it.

PeterT · 07-22-2022, 07:02 PM

Have you tried just updating the video drivers to a current one?

Sent from my Pixel 4a using Tapatalk

quoddle · 07-23-2022, 05:06 AM

Video drivers are all current.
It wasn't as simple as turning off update services. It was numerous changes in the registry which he can't remember now as it was several years ago so I'm stuck with this version unless I do a complete new install.
The PC works fine with everything else, the issue seems to be the lack of backwards compatibility of the new Calibre and Qt6

07-22-2022, 07:32 AM	#1
quoddle Enthusiast Posts: 45 Karma: 10 Join Date: Oct 2009 Device: Kobo Libra H20	Upgrade W10 64bit Hi, I've been trying to upgrade to Calibre 6.1 on a 64bit W10 pc running Windows Defender. It installs normally but when I run it I get "This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem. Available platform plugins are: direct2d, minimal, offscreen, Windows" I've tried reinstalling several times with the same result. I've had to uninstall and go back to 5.44 which woks fine. Anything I can do to get the new version working?

07-22-2022, 10:40 AM	#5
georgemk Addict Posts: 243 Karma: 291844 Join Date: Oct 2019 Device: Kobo Nia	@quoddle Looking on the internet for that error message, it seems that this error occurs where you have 2 or more programs each with their own version of the QT software (which Calibre uses too) and the interactions between them. Basically 1 program finds the wrong QT files at runtime (an incompatible version) and the result is this message. Have a look in your "System Environment Variables" for any variable name starting with QT and if found see what software uses it. That is one possible cause as it would divert Calibre from loading its QT files and try to load another program's version. Don't just delete any such variable you find but investigate as you could stop something else working - you'd be surprised at how many programs use QT behind the scenes. Last edited by georgemk; 07-22-2022 at 10:42 AM. Reason: Add be careful

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07-22-2022, 09:04 AM	#3
BetterRed null operator (he/him) Posts: 21,725 Karma: 29711016 Join Date: Mar 2012 Location: Sydney Australia Device: none	Moderator Notice Moved from the Issues after updating to calibre 6.1 64 bits thread. BR

07-22-2022, 09:54 AM	#4
quoddle Enthusiast Posts: 45 Karma: 10 Join Date: Oct 2009 Device: Kobo Libra H20	Tried that but the same error in Safe Mode. Startup Repair went through the Diagnosing your PC stage then came up with Startup Repair couldn't repair your PC. Everything else works fine it's just the new version of Calibre that won't run.

07-22-2022, 10:56 AM	#6
quoddle Enthusiast Posts: 45 Karma: 10 Join Date: Oct 2009 Device: Kobo Libra H20	It's not listed there at all. Do I need to manually install it?

07-22-2022, 11:10 AM	#7
kovidgoyal creator of calibre Posts: 45,347 Karma: 27182818 Join Date: Oct 2006 Location: Mumbai, India Device: Various	That's the error you get trying to run calibre 6 on windows 8. Are you sure you are on windows 10?

07-22-2022, 11:12 AM	#8
quoddle Enthusiast Posts: 45 Karma: 10 Join Date: Oct 2009 Device: Kobo Libra H20	Yes, Windows 10 Pro though an old version

07-22-2022, 05:32 PM	#11
JSWolf Resident Curmudgeon Posts: 79,750 Karma: 145864619 Join Date: Nov 2006 Location: Roslindale, Massachusetts Device: Kobo Libra 2, Kobo Aura H2O, PRS-650, PRS-T1, nook STR, PW3	I'm taking a guess that maybe Qt6 is not compatible with older versions of Windows 10.

07-22-2022, 05:36 PM	#12
quoddle Enthusiast Posts: 45 Karma: 10 Join Date: Oct 2009 Device: Kobo Libra H20	That's what it looks like. Unfortunately my copy of Windows was modified several years ago by my son in law to stop it updating as the updates were causing more problems than they solved. It's been fine ever since until this problem with Calibre. The only way I can update is a clean install which I don't want to do as it'll take me forever to reinstall everything. Looks like I'm stuck with v5.44

07-22-2022, 07:02 PM	#14
PeterT Grand Sorcerer Posts: 13,511 Karma: 78910202 Join Date: Nov 2007 Location: Toronto Device: Libra H2O, Libra Colour	Have you tried just updating the video drivers to a current one? Sent from my Pixel 4a using Tapatalk

07-23-2022, 05:06 AM	#15
quoddle Enthusiast Posts: 45 Karma: 10 Join Date: Oct 2009 Device: Kobo Libra H20	Video drivers are all current. It wasn't as simple as turning off update services. It was numerous changes in the registry which he can't remember now as it was several years ago so I'm stuck with this version unless I do a complete new install. The PC works fine with everything else, the issue seems to be the lack of backwards compatibility of the new Calibre and Qt6

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