No QcoreApplication Found - Spyder 5 installation problem

[agos316]

During installation of spyder 5 on Ubuntu 20.04. The following error appears.

"No QCoreApplication instance found. Application patches not applied. You have to call load_stylesheet function after instantiation of QApplication to take effect. "

The IDE doesn't launch.

Is there a way to fix this ?

[ITWARRIORS-Kilian]

I have a similar problem.

i have not found a solution yet, but when running it with python to get the error logs, it seems like that during the init spyder is not able to find all icons. The first one was mdi.check-bold, which i testwise replaced for now, but now i am having the same problem with mdi.content-save-edit

@agos316 Did you also use pip for installing spyder?

[agos316]

I installed using conda. I really like this IDE so I hope the problem is fixed soon.

I checked all the dependencies and everything seemed to be in line.

[emmaworthington]

Same error for Spyder 5 installed using miniconda on MacOS Catalina 10.15.7.

A fix or workaround would be greatly appreciated! I've reverted to 4.2.5 for the moment.

[ITWARRIORS-Kilian]

okay i moved on and also replaced couple of the other icons that were not found.
(when running the program from with in python ==> i got exception messages like this:

Exception: Invalid icon name "source-repository" in font "mdi"

I than replaced them by modifing the corresponding lines in the file: icon_manager.py which you can find in:
"your python install folder"/Lib/site-packages/spyder/utils

In this file you will find a class called IconManager which has an attribute called _qtaargs. This attribute seems to be a big dictonary mapping some operation to the corresponding icons. There one can find the "invalid icon names" in the form font.icon_name. I replaced them with some icon that seemed familiar with the required one. So e.g I replaced the above one with mdi.source-commit.

I will attach my modified version of the file. But this should definitely be only a temporary fix and i am not 100% confident that this might also help you (needed to change file type to txt ;))
icon_manager.py.txt.

Now it at least starts. Even though it still has a bug with the icons (see the attached screenshot).

It also gives me now in spyder on the gui the error message, that i have the wrong version of spyder-kernels, which i so far tried to solve by updating it with pip. Which told me that spyder kernels would be allready on the newest version.

[agos316]

Wow @ITWARRIORS-Kilian thats pretty cool that you got it to run,I might try this, I hope a long term solution is available soon.

[dalthviz]

Hi @agos316 thanks for the feedback! Regarding the message No QCoreApplication found... I think is just a warning. However seems like an error regarding the mapping of the icons is preventing Spyder to launch (if you are having a similar issue as @ITWARRIORS-Kilian).

@agos316 or @emmaworthington could you check if running Spyder with the --debug-info verbose flag gives us more information to check a possible traceback before Spyder crashes? (Like for example the errors mentioned by @ITWARRIORS-Kilian regarding being unable to load some icons). Also, could you provide more information about your setup (dependencies, OS, an in general the information requested in the issue template)? Any new info is greatly appreciated!

@ITWARRIORS-Kilian about the pop-up dialog saying that the spyder-kernels version is incorrect, it was a bug but we already solve it at #15100 . Similarly with the icons in the menus and actions, we also did some fixes for that. Those fixes will be soon available (they will be released inside Spyder 5.0.1)

@agos316 @emmaworthington in terms of a workaround, if the launching problem is related with the icons, you could try to use the Spyder 2 icon-set. For that you need to locate the file where Spyder saves its preferences (usually at <user directory or home directory>/.spyder-py3/config/spyder.ini) and inside the file change the icon_theme value from spyder 3 to spyder 2

Let us know if something of the above helps! (or at least helps clarifying the status of things :) )

[agos316]

@dalthviz I ran the debug, and it led to the same call back.

File "/home/qtconsole/util.py", line 64, in new
QClass.init(inst)
TypeError: init() missing 1 required positional argument: 'context'

Here is what it says after before closing out

[dalthviz]

Thank you for the response @agos316 in that case the issue is related with a new release of jupyter_client could you downgrade to jupyter_client=6.1.12 and test again, please?

[agos316]

@dalthviz That did it ! Thank you for your help

Thanks to all that replied as well

[dalthviz]

@ITWARRIORS-Kilian could you open a new issue for the errors you were experiencing with the icons, please? Seems like the issue here was different. Thanks!

@emmaworthington let us know if downgrading jupyter_client helps in your case too

[mrclary]

I can confirm that "No QCoreApplication instance found. Application patches not applied. You have to call load_stylesheet function after instantiation of QApplication to take effect. " is present for bootstrap on macOS and the macOS application but does not inhibit launching.

Also, regarding jupyter_client=6.1.13, see #15180.

[yiorgosn]

I also confirm the same error for Spyder 5 installed using conda on Win10 20H2 but the application launches and works. The jupyter_client fix did not eliminate the error message.

I also get the spyder-kernels 2.0.1 version not being present but checking via anaconda the proper version is there for the environment.

The only issue for me seems to be the icons overlapping with menu and tab items, see the tab overlap with the navigation arrows in the picture below

[ccordoba12]

@yiorgosn, that will also be fixed in 5.0.1, to be released shortly.

[emmaworthington]

Hi,
I get the warning "No QCoreApplication instance found. Application patches not applied. You have to call load_stylesheet function after instantiation of QApplication to take effect." but the application launches okay. My jupyter-client version was already 6.1.12.

I also get the spyder-kernels missing dependencies popup, but I have v2.0.1 installed by conda.

Thanks

[ccordoba12]

Hey @emmaworthington, you said

also get the spyder-kernels missing dependencies popup, but I have v2.0.1 installed by conda.

That's a duplicate of issue #15091 and it'll be fixed in our next version (5.0.1), to be released shortly.

[richlysakowski]

Carlos, Thanks for your and your team's great work and being so responsive. Spyder is awesome and I love the job you all do!

[jamesmhbarry]

I get this warning on Ubuntu 18.04 as well, although Spyder still launches

[dalthviz]

Hi @jamesmhbarry yep is just a warning but since it could be kind of misleading (you could think something bad is happening) we are thinking to remove/hide it in a future release