Been using calibre forever without issue, but the other day it began misbehaving. Every time I connect my phone, it closes. Works perfectly if my phone is not connected. I am running version 3.46.
Grabbed a debug log, in case that might be useful:
Spoiler:
calibre Debug log
calibre 3.46 [64bit] embedded-python: True is64bit: True
Windows-10-10.0.17763-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.17763')
Python 2.7.15+
Windows: ('10', '10.0.17763', 'SP0', u'Multiprocessor Free')
Interface language: None
Successfully initialized third party plugins: DeDRM (6, 6, 3)
calibre 3.46 [64bit] embedded-python: True is64bit: True
Windows-10-10.0.17763-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.17763')
Python 2.7.15+
Windows: ('10', '10.0.17763', 'SP0', u'Multiprocessor Free')
Interface language: None
Successfully initialized third party plugins: DeDRM (6, 6, 3)
Turning on automatic hidpi scaling
devicePixelRatio: 1.0
logicalDpi: 120.0 x 120.0
physicalDpi: 141.76744186 x 141.402061856
Using calibre Qt style: True
[0.00] Starting up...
[0.00] Showing splash screen...
[0.11] splash screen shown
[0.11] Initializing db...
[0.14] db initialized
[0.14] Constructing main UI...
[1.62] main UI initialized...
[1.62] Hiding splash screen
[3.70] splash screen hidden
[3.70] Started up in 3.70 seconds with 486 books
Job: 0 Get device information started
DeviceJob: 0 Get device information done, calling callback
DeviceJob: 0 Get device information callback returned
Job: 1 Set library information started
DeviceJob: 1 Set library information done, calling callback
DeviceJob: 1 Set library information callback returned
Job: 2 Get list of books on device started
MTP: Loading filesystem metadata...
MTP: Ignored object: Pictures
MTP: Ignored object: Music
MTP: Ignored object: Movies
MTP: Ignored object: DCIM
MTP: Ignored object: Ringtones
MTP: Ignored object: Android/media
MTP: Ignored object: Android/obb
MTP: Ignored object: Android/data/com.google.android.GoogleCamera
MTP: Ignored object: Android/data/com.google.android.apps.translate
MTP: Ignored object: Android/data/com.oneplus.note
MTP: Ignored object: Android/data/com.microsoft.teams
MTP: Ignored object: Android/data/com.bmo.mobile
MTP: Ignored object: Android/data/com.ubercab
MTP: Ignored object: Android/data/com.slido.app
MTP: Ignored object: Android/data/com.peoplefun.wordcross
MTP: Ignored object: Android/data/com.flyersoft.moonreaderp
MTP: Ignored object: Android/data/com.tumblr
MTP: Ignored object: Android/data/com.rocketlanguages.app
MTP: Ignored object: Android/data/tesmath.calcy
MTP: Ignored object: Android/data/com.matteljv.uno
MTP: Ignored object: Android/data/com.rarlab.rar
MTP: Ignored object: Android/data/com.google.android.apps.docs.editors.docs
MTP: Ignored object: Android/data/com.google.android.tts
MTP: Ignored object: Android/data/com.mindbodyonline.connect
MTP: Ignored object: Android/data/com.skipbo.game
MTP: Ignored object: Android/data/com.android.vending
MTP: Ignored object: Android/data/cn.oneplus.photos
MTP: Ignored object: Android/data/com.mxtech.videoplayer.ad
MTP: Ignored object: Android/data/com.apps.picturepick
MTP: Ignored object: Android/data/com.google.android.apps.photos
MTP: Ignored object: Android/data/app.goranger.android
MTP: Ignored object: Android/data/com.google.android.apps.docs
MTP: Ignored object: Android/data/com.nook.app
MTP: Ignored object: Android/data/com.google.android.youtube
MTP: Ignored object: Android/data/com.whova.event
MTP: Ignored object: Android/data/com.netflix.mediaclient
MTP: Ignored object: Android/data/com.google.android.apps.maps
MTP: Ignored object: Android/data/com.apcurium.MK.CasinoTaxi
MTP: Ignored object: Android/data/net.oneplus.push
MTP: Ignored object: Android/data/com.google.android.gms
MTP: Ignored object: Android/data/net.oneplus.weather
MTP: Ignored object: Android/data/com.nianticlabs.pokemongo
MTP: Ignored object: Android/data/com.google.android.googlequicksearchbox
MTP: Ignored object: Android/data/com.doubleTwist.androidPlayer
MTP: Ignored object: Android/data/com.facebook.orca
MTP: Ignored object: Android/data/com.duolingo
MTP: Ignored object: Android/data/com.oneplus.gallery
MTP: Ignored object: Android/data/com.timeplay
MTP: Ignored object: Android/data/com.facebook.katana
MTP: Ignored object: Android/data/com.google.android.apps.fitness
MTP: Ignored object: Android/data/com.google.android.inputmethod.japanese
MTP: Ignored object: Android/data/com.evernote
MTP: Ignored object: Android/data/com.oneplus.card
MTP: Ignored object: Android/data/com.estrongs.android.pop
MTP: Ignored object: Android/data/com.cutcom.apparmor.dal
MTP: Ignored object: Android/data/com.atlassian.android.jira.core
MTP: Ignored object: Android/data/com.opera.browser
MTP: Ignored object: Android/data/com.google.android.apps.docs.editors.sheets
MTP: Ignored object: Android/data/com.google.android.gm
Job: 0 Get device information finished
No details available.
Job: 1 Set library information finished
No details available.
I also found this thread, but there does not appear to be a devicedriver<DEVICENAME> file in my configuration folder.
There are a few MTP devices that cause unexplained crashes on windows. Sadly I have never been able to reproduce so fixing it is difficult. You can try the following mitigations: