TimedRotatingFileHandler not working correctly with PyInstaller

[Alexander Bauer]

Hi, 

I'm using a TimedRotatingFileHandler for my logs, to rotate the logs at midnight. The mode to open the log files for this handler is hard-coded to mode="a", which means, it should always append to already existing logs for this day, which works fine as long as I start the scripts manually from shell. 

But as soon as I pack the script with PyInstaller, an already existing file for this day is overwritten when the application starts. Does anybody have an idea why this happens?

Thanks in advance for any advice.