My Photos.app starts on system startup Apple's new Photos.app starts on every system startup although there is no configuration settings for system startup.

Here is my checklist:


Users &amp; Groups > Login Items (There is no config for Photos)
Right click photos in Dock > Options > Launch on system startup (There is no config for Photos)


Here is my another what I did


Disabling and re-enabling iCloud Photos
Repairing Photos library from this tutorial
If Dropbox affect Photos for starting at system launch, I disable Dropbox's photos settings.


How can I prevent Photos.app on system startup without deleting it?
You probably have a SD card or a device which stores photos plugged in your Mac.

To prevent Photos from auto-opening, follow these instructions:


  
  Connect the iPhone, camera, SD card, etc to the Mac and let Photos app launch itself as usual
  Under the “Import” tab of Photos app, look in the upper left corner to find the device name, this will indicate which hardware will no
  longer automatically activate Photos app
  Click the checkbox so that “Open Photos for this device” is no longer selected (likewise, toggling this on would enable Photos app to
  open itself again automatically when this device is connected)
  Quit out of Photos app, the change is immediate for that device – this can be switched back at any time in the same OS X Photos app
  
  
  


Via: http://osxdaily.com/2015/05/31/stop-photos-opening-automatically-mac-os-x/