[QGIS-Developer] QGIS API (PyQGIS) doesn't properly read layers

[Piotr]

I have a problem with reading qgs file by PyQGIS lib. I'm creating 
python standalone stript which externally use PyQGIS from installed QGIS 
desktop application. *The problem is that PyQGIS sometimes read qgs file 
but WITHOUT READING LAYERS INSIDE*. I'm using Ubuntu 18.04 LTS, django, 
python 3.6.9, QGIS 3.4.14-Madeira

PyQGIS helps me with reading and updating .qgs files. I'm always using 
same start and ending code.

|fromqgis.core importQgsProject,QgsApplicationapp 
=QgsApplication([],False)app.initQgis()app.exit()project 
=QgsProject.instance()project.read("/path/to/file.qgs")(PyQGISoperations)project.write()app.exit()|

And... the problem is that this code works fine... but never know how 
long, sometimes few days or few weeks but finally comes the moment when 
this code stops working properly. It still reads .qgs file but without 
layers inside, see groups but not layers. It should be impossible that 
code works fine for long time but some day it stops.

PyQGIS unfortunately works that way. The only thing comes to my mind is 
that the problem may be inside qgis desktop because PyQGIS is not common 
library. I belongs and works only with qgis desktop. This program maybe 
remember reading states or use multithreading with the way which i don't 
understand.

Of course, the problem may be completely different but i really don't 
have any more ideas how to change this code.

*Does anyone know how to fix it?*

Some logs from app which makes me wonder, maybe this will help.

|WARNING:QApplicationwas notcreated inthe main()thread.Loadinga file 
that was saved withan older version of qgis (saved 
in3.4.13-Madeira,loaded in3.4.14-Madeira).Problemsmay 
occur.QObject::~QObject:Timerscannot be stopped fromanother thread 
QObject::~QObject:Timerscannot be stopped fromanother thread 
QObject::connect:Cannotqueue arguments of type 'QDomDocument'(Makesure 
'QDomDocument'isregistered using qRegisterMetaType().)|

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