VS 2021 crash "could not find the Qt platform plugin"

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JBR48
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VS 2021 crash "could not find the Qt platform plugin"

Post by JBR48 »

First post on this forum. I recently bought the VS2021 upgrade. I had VS2019 installed before and it worked fine.
After installation the program seems to start up normally, but after completely loading, it will present a requester with a cryptic message.

"This application failed to start because it could not find or load the Qt platform plugin "windows" in "".
Available platform plugins are windows.
Reinstalling the application may fix this problem."

Closing the requester will immediately terminate the program. Note that before closing the requester the program seems to work normal, I can insert video clips and generate an output video.

I contacted support and it gave me a series of instructions to determine the problem, involving WinAudit and MSINFO23 reports. Then came a sequence of actions involving uninstalling VS2019, uninstalling and re-installing VS2021 several times without any change in results. I finally stopped this, because I was afraid I might wear out my computer's reset switch :) .

I got the feeling that tech support was mindlessly following their scripts and did not address the actual problem. One question that I would have is that VS2021 seems to use the Qt framework and the problem is clearly with the setup of that framework. Perhaps there is a conflict between some software that I already use and the Qt framework.
  1. Is the Qt framework used in the main application or is it used only in a helper function that I could perhaps disable or uninstall?
  • Perhaps I could install Qt libraries from another source and install and test those separately? I have used Qt under Linux, so I am somewhat familiar.
Given some time I could probably come up with more debugging strategies, but before I spent too much time, I was wondering if any members have experienced similar problems or perhaps have other suggestions. I look forward to your thoughts.
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Re: VS 2021 crash "could not find the Qt platform plugin"

Post by Ken Berry »

Welcome to the forum.

Your problem is totally new to me, unfortunately. I've been on this forum for a long time, and this is the first time I have heard of this (or as much as my ageing brain can recall!) When I saw "Qt" I immediately thought it was a Quicktime problem. But of course on googling it, I see it is deeper than that. Hopefully someone who knows more about it will come along soon to help you.

I assume, however, that you have already googled it yourself. There seem to be quite a few "solutions" out there. One caught my eye in that it contains quite a few relatively clear steps. But it is at least worth reading if you have not already: https://forum.qt.io/topic/90293/could-n ... dows-in/14
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JBR48
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Re: VS 2021 crash "could not find the Qt platform plugin"

Post by JBR48 »

Hello Ken,

Thank you for the quick reply. I totally missed your google result, I probably included VideoStudio in all my searches. The discussion in that thread is talking about the exact same error message that I get, so it is very relevant. The solution given is to remove a directory from the global PATH that contains the wrong version of qwindows.dll.
In my case it turns out that I have 37 (!) instances of qwindows.dll somewhere on my computer, but none of them are on the global PATH. Also VideoStudio does not have qwindows.dll anywhere in its installation.

One possibility is that some VideoStudio component does require Qt, but it is missing from the installation. That would explain the message that the Qt platform plugin cannot be found. I will follow up this line of investigation.

Regards,
Jan
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Re: VS 2021 crash "could not find the Qt platform plugin"

Post by lata »

Jan…..
I have searched my C:Drive for qwindows.dll finding 16 entries
Associated with the Corel Installation are............

C:\Program Files\Corel\Corel AfterShot 3\build\Plugins\platforms
C:\Program Files (x86)\NewBlueFX\Common\platforms
C:\Program Files\NewBlueFX\Common\platforms
C:\Program Files\NewBlueFX\Titler\platforms

New BlueFX is installed by Video Studio Ultimate as part of the Bonus Features folder, shows as NewBlue Titler Pro 5 in the FX library
Re-Installing Video Studio may not remove the NewBlueFX folder nor remove “qwindows.dll”

You would be best to view Program and Features for NewBlue Titler Pro for Corel or Titler FX entries, uninstall then delete or rename the NewBlueFX
Now try running Video Studio 2021

Install the package from Bonus Features folder by running the "setup_Bonus.exe", or re-install the entire VS 2021 program
Your download program files …… \64bit\BonusFeature

That should replace the “qwindows.dll” file

If the problem persists I would download the installation files again to a new empty folder -- just in case the original downloaded installation files are corrupt
You would have to uninstall 2021 to download the files again.
Regards Trevor
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Re: VS 2021 crash "could not find the Qt platform plugin"

Post by JBR48 »

The google link that Ken gave me was the crucial link to solving my problem. But in contrast to the problem in the google link my problem was not that the wrong qwindows.dll was on the $PATH$, because it wasn't. But there were directories for NewBlueFX in both C:\Program Files (x86) and C:\Program Files. NewBlueFX is of course part of (older) VideoStudio installations, which were not uninstalled automatically, but still managed to affect the newest installation of VS2021. Removing those directories immediately solved the program crash.

I was now afraid that I had removed the NewBlueFX functionality from my computer, but it turns out that that functionality is now wholly contained in the directory C:\Program Files\Corel\Corel VideoStudio 2021\vft_plug. There are no longer separate NewBlueFX directories.

The strange part is why VS2021 keeps looking for qwindows.dll in the old directories, while it now has moved this functionality to a new place. I cannot imagine that my computer is the only one that has (remnants of) older VideoStudio installations floating around. I think I had 10 separate VideoStudio versions installed at some point :D (maybe not all on my current computer). Clearly some stray code in VS2021 remaining from previous versions? Tech support should take a look at that.

Update I have now had time to read the post by lata. He gives the correct analysis of this problem and I thank him for contributing. I have a few remarks:

He finds the qwindows.dll in the same places as I did. His advice to uninstall NewBlue is excellent, but I was not able to locate a way to uninstall, since it was no longer in the Apps & Features list. Just deleting the directories seemed to do the trick, however. Re-installing the bonus features was also not necessary, since they were correctly installed the first time. Also the VideoStudio2021_Installer.exe seems to pull everything from the internet, there do not appear to be folders with bonus software like ..\64bit\BonusFeature anymore.
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Re: VS 2021 crash "could not find the Qt platform plugin"

Post by lata »

JBR48 wrote:
Sat Apr 10, 2021 9:42 pm
Update I have now had time to read the post by lata. He gives the correct analysis of this problem and I thank him for contributing. I have a few remarks:

He finds the qwindows.dll in the same places as I did. His advice to uninstall NewBlue is excellent, but I was not able to locate a way to uninstall, since it was no longer in the Apps & Features list. Just deleting the directories seemed to do the trick, however. Re-installing the bonus features was also not necessary, since they were correctly installed the first time. Also the VideoStudio2021_Installer.exe seems to pull everything from the internet, there do not appear to be folders with bonus software like ..\64bit\BonusFeature anymore.
When we purchase Video Studio or install the trial we are provided with a small file called “VideoStudio_Install.exe”
If you are lucky then it will be called “VideoStudio2021_Installer.exe” that identifies the version, other wise 2021 version file is 7,091Kb

Think of the file “VideoStudio2021_Installer.exe” as a download / Installer manager.
Running this will allow us to enter our serial number, register then proceed to download and install the program
The downloaded files are saved by default to the desktop in a folder aptly called “VideoStudio2021”
We do have the option to choose another save location should we wish to do so.
The total size being 5.7Gb ish

Here you should find the installation files containing folders………..
64bit, Common, StandardContent2 and also a copy of VideoStudio_Install.exe
Viewing the contents of 64bit you should find the Bonus Features, that is assuming you have purchased the Ultimate version and not the Basic Pro version

Re-installing 2021
This will use the same process as above and will also check the existing files for any changes / updates on the Corel server to download any new files to the same save location
If you wish to download the complete package again then choose a new empty save location folder, the web installer will then download all files again, useful if we think the first download files were corrupt.


Program and Features entry for NewBlue Titler Pro for Corel may not be showing even though the plugin is installed, this may be a problem with multiple installations of 2019 and 2021 (Version Collisions)
Should the fixed by running Bonus Features "setup_Bonus.exe" for 2021.

OK
NewBlueFX
If you have either renamed or deleted the folder NewBlueFX from C:\Program Files\NewBlueFX then the filter in FX library although will show will not work giving an error when trying to use.
However if Video Studio and NewBlue is working with no qwindows.dll. errors then I guess you have fixed the original issue.
Regards Trevor
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