[JimmXinu]

I have used a Reading List set to 'Sync this device as soon as connected' to send new/changed books to my Kindle for years. Generally, several times a day.

Since the release of Calibre 7, I have had an intermittent problem: After connecting the Kindle, and part way through sending to Kindle Calibre just hangs and I have to kill Calibre. Happens perhaps 1 time in 10?

Turning off 'Sync when connected' on the list and instead calling RL's 'Sync Now' manually doesn't seem to have the same problem.

I think this is an interaction between Calibre 7 and RL? Did something change in the device connected hook? I'm hoping somebody has an idea.

I have not been able to replicate this on demand, but here's a debug I captured:

Spoiler:

calibre 7.6  embedded-python: True
Windows-10-10.0.19045-SP0 Windows ('64bit', 'WindowsPE')
('Windows', '10', '10.0.19045')
Python 3.11.5
Windows: ('10', '10.0.19045', 'SP0', 'Multiprocessor Free')
Interface language: None
EXE path: c:\Program Files\Calibre2\calibre-debug.exe
Successfully initialized third party plugins: DeDRM (10, 0, 3) && ColumnSum (2, 2, 0) && Count Pages (1, 13, 5) && EpubMerge (2, 17, 1) && EpubSplit (3, 6, 1) && FanFicFare (4, 32, 4) && Favourites Menu (1, 3, 0) && Find Duplicates (1, 10, 8) && Generate Cover (2, 3, 3) && Jimms Editor Addons (0, 0, 1) && Manage Series (1, 5, 2) && Modify ePub (1, 8, 2) && Quality Check (1, 13, 8) && Reading List (1, 15, 1) && ScrambleEbook (0, 6, 0) && SmartEject (2, 5, 0) && SpacerName (0, 0, 2) && SplitMergeNew (0, 3, 0) && View Manager (1, 10, 2)
QPA platform: windows
devicePixelRatio: 2.0
logicalDpi: 96.0 x 96.0
physicalDpi: 141.7674418604651 x 141.4020618556701
ApplicationPaletteChange event ignored
Using calibre Qt style: True
[0.00] Starting up...
[0.00] Initializing db...
[0.55] db initialized
[0.55] Constructing main UI...
qt.webengine.QWebEngineView OK
[4.25] GUI main window shown
EpubMerge: DEBUG: 2024-03-09 10:00:03,105: calibre_plugins.epubmerge.epubmerge_plugin(156): macmenuhack file_path:C:\Users\USER\AppData\Roaming\calibre\plugins\fanficfare_macmenuhack.txt
FFF: DEBUG: 2024-03-09 10:00:03,153: calibre_plugins.fanficfare_plugin.fff_plugin(215): Plugin FanFicFare macmenuhack file_path:C:\Users\USER\AppData\Roaming\calibre\plugins\fanficfare_macmenuhack.txt
[4.55] main UI initialized...
[4.55] Started up in 4.55 seconds with 6421 books
Storage number map:
{(7, 0): [(3, 'C')], (7, 1): [(1, 'E')]}
Storage number for USBSTOR\DISK&VEN_KINDLE&PROD_INTERNAL_STORAGE&REV_0401\G8S0PP12127604KM&0: StorageDeviceNumber(type=7, number=1, partition_number=0)
Drive letters for USBDevice(vendor_id=0x1949 product_id=0x324 bcd=0x401 devid=usb\vid_1949&pid_0324&rev_0401 devinst=13)
{'drive_letters': ['E'],
 'pnp_id_map': {'E': '\\\\?\\usbstor#disk&ven_kindle&prod_internal_storage&rev_0401#g8s0pp12127604km&0#{53f56307-b6bf-11d0-94f2-00a0c91efb8b}'},
 'readonly_drives': set(),
 'sort_map': {'E': (1, 1)}}
Syncing cover thumbnails to workaround amazon cover bug
Restored 0 cover thumbnails that were destroyed by Amazon
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
DEBUG:    0.0 USBMS: Fetching list of books from device. Device= KINDLE2 oncard= None
DEBUG:    0.0 USBMS: dirs are: E:\ documents
Job: 0 Get device information finished
No details available.
Job: 1 Set library information finished
No details available.
DEBUG:    3.9 USBMS: scan from root False E:\documents
DEBUG:   15.4 USBMS: count found in cache: 6424, count of files in metadata: 6424, need_sync: False
DEBUG:   15.4 USBMS: Finished fetching list of books from device. oncard= None
DEBUG:   15.4 USBMS: Fetching list of books from device. Device= KINDLE2 oncard= carda
DEBUG:   15.4 USBMS: Fetching list of books from device. Device= KINDLE2 oncard= cardb
DeviceJob: 2 Get list of books on device done, calling callback
DeviceJob: metadata_downloaded: Starting set_books_in_library
DeviceJob: set_books_in_library: books to process= 6424
DeviceJob: set_books_in_library finished: time= 0.07103323936462402
DeviceJob: metadata_downloaded: updating views
DeviceJob: metadata_downloaded: syncing
DeviceJob: metadata_downloaded: refreshing ondevice
DeviceJob: metadata_downloaded: sending metadata_available signal
READING LIST: Metadata available: {'main': {'last_library_uuid': 'f835a254-143e-4293-c466-d075973e44a4', 'calibre_version': '7.6.0', 'prefix': 'E:/', 'location_code': 'main', 'date_last_connected': '2024-03-09T16:00:37.319530+00:00', 'device_name': 'Kindle PaperWhite', 'device_store_uuid': 'c0ba076f-fcad-78eb-b14c-e81c0ac77f64'}}
READING LIST: Sync Now - force_sync= False
READING LIST: Device found to sync to: Kindle PaperWhite c0ba076f-fcad-78eb-b14c-e81c0ac77f64
READING LIST: Syncing 6 books in 'Add to Kindle' to: b0ba076f-fcad-78eb-b14c-f81c0ac77f64 (location:None)
DeviceJob: 2 Get list of books on device callback returned
Job: 3 Upload 6 books to the device: Tome of the Orange Sky, Little Hunter, Star Wars: The Force Wills, Return of the Stellar Empress, Nemesis, A Meeting that changed the Galaxies started
Device using plugboard azw3 KINDLE2 [['{#title_prefix:|| }{series:|| }{series_index:0>2s|| - }{title}{#wordcount:| (|)}{tags:| |}{#extranotes:| - |}', 'title'], ["{authors:shorten(215,'-',0)}", 'authors']]
Setting metadata in: Tome of the Orange Sky at: C:\Users\USER\AppData\Local\Temp\calibre_20o1sbx9\i802oqe2caltmpfmt.azw3
Job: 2 Get list of books on device finished
No details available.
Device using plugboard azw3 KINDLE2 [['{#title_prefix:|| }{series:|| }{series_index:0>2s|| - }{title}{#wordcount:| (|)}{tags:| |}{#extranotes:| - |}', 'title'], ["{authors:shorten(215,'-',0)}", 'authors']]
Setting metadata in: Little Hunter at: C:\Users\USER\AppData\Local\Temp\calibre_20o1sbx9\11qzndq_caltmpfmt.azw3