can't find or load Qt platform plugin "windows"


When I’m trying to run any Deadline application (Slave, Launcher, Monitor or etc.), I’m getting the following error:


I’ve uninstalled and reinstalled Deadline Client couple of times but nothing changed. Anyone knows what might be causing this?


Check “C:\Windows\System32” for files starting with Qt and ended in “dll” and move them somewhere safe, then try starting Deadline again.

Some apps throw Qt in there and it breaks everyone else who’s using a different version.

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It was exactly caused because of that!

Thanks a lot!!

Okay, that probably broke something else. When you find out, can you let me know? We should talk to them about getting those DLLs somewhere safer.

Hi @eamsler,

I have the same problem, but I can’t find any QT files in system32 folder…
Can you help me?


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If you’re on Deadline 10.0 and up, search your entire system for “Qt5Core.dll”. The tricky thing with Windows is how it searches for libraries to load. Here’s the process Windows takes but it’s fairly technical:

If you do find QtCore5.dll somewhere that would be system-wide (usually under “C:\Windows” somewhere) try and figure out which app installed it and remove it. I expected if you just deleted the Qt files whatever application depended on it will stop working.

Just to tack on to this discussion since I just started having this same issue with one of my machines this morning.

This morning this machine had a full lockup, it was completely inaccessible and I had to Force shut it down by long pressing the power, Not a great way to wake up.

After restarting I had the same error:
Failed to load

I checked the path and everything seems correct.

I looked in C:\Windows\System32 and nothing that starts with Qt*

I also searched the whole machine and found only a few instances of Qt5core.dll, the lenovo ones aren’t in the path and were installed yesterday when everything worked.

I have uninstalled everything except the license server from this machine since everything is currently point to it.

I have tried reinstalling all the applications a number of times without success.

I have even done a sfc /scannow on the machine but also without success.

In a little bit of desperation I tried installing another application to see what would happen. I tried reinstalling the repository and it failed to install because it said it could not check the version of MongoDB that it had downloaded. This machine is no longer running the repo or database it’s been moved to another machine.

I went over to the temp path and tried running mongo.exe --version directly and got the error that VCRUNTIME140.dll was missing a little more searching and I found that repairing Microsoft Visual c++ 2015-2019 Redistributable (x64) 14.26.28720 by going to Add Remove Programs > Modify and Repair fixed Mongo being able to check it’s version.

I then tried running Monitor and… IT WORKED!

No idea what originally caused this issue but if anyone runs into it and dllhell doesn’t fix it it could be the VCRuntime.

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