What does this error mean? (windows10)

7e-ross · 12-21-2025, 11:02 PM

As of the last 24 hours, Calibre will launch, with splash screen, but the window will be invisible. Task manager will acknowledge it is running, but hovering over the taskbar icon will show an empty window. Rolled it all the way back to v7.15 in hopes of getting something and finally caught an error message.

"calibre, version 7.15.0
ERROR: Startup error: There was an error during calibre startup. Parts of calibre may not function. Click "Show details" to learn more.

Traceback (most recent call last):
File "calibre\gui2\main.py", line 307, in initialize_db_stage2
File "calibre\gui2\main.py", line 250, in start_gui
File "calibre\gui2\ui.py", line 247, in initialize
File "calibre\gui2\layout.py", line 333, in init_main_window_mixin
File "calibre\gui2\bars.py", line 757, in __init__
File "calibre\gui2\bars.py", line 823, in apply_settings
KeyError: 'mid-small' "

Help would be appreciated.

kovidgoyal · 12-21-2025, 11:23 PM

Do not downgrade calibre randomnly, your error message comes from doing that. Updgrade again and it will go away

12-21-2025, 11:02 PM	#1
7e-ross Junior Member Posts: 2 Karma: 10 Join Date: Dec 2025 Device: Kindle Fire 7	What does this error mean? (windows10) As of the last 24 hours, Calibre will launch, with splash screen, but the window will be invisible. Task manager will acknowledge it is running, but hovering over the taskbar icon will show an empty window. Rolled it all the way back to v7.15 in hopes of getting something and finally caught an error message. "calibre, version 7.15.0 ERROR: Startup error: There was an error during calibre startup. Parts of calibre may not function. Click "Show details" to learn more. Traceback (most recent call last): File "calibre\gui2\main.py", line 307, in initialize_db_stage2 File "calibre\gui2\main.py", line 250, in start_gui File "calibre\gui2\ui.py", line 247, in initialize File "calibre\gui2\layout.py", line 333, in init_main_window_mixin File "calibre\gui2\bars.py", line 757, in __init__ File "calibre\gui2\bars.py", line 823, in apply_settings KeyError: 'mid-small' " Help would be appreciated.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Move My Digital Editions from Documents in Windows10	MRM66	Windows Devices	4	04-18-2022 08:28 AM
Calibre Hudl 2: calibre, version 3.2.1 ERROR: Error: Error communicating with device	elfed	Devices	4	07-21-2017 06:33 AM
Nook Simple Touch will suddenly not work in Windows10	Hohenrain	Devices	6	07-10-2017 01:13 PM
Calibre crashes in Windows10	setherd	Calibre	3	08-04-2015 05:36 AM
calibre, version 0.8.8 ERROR: Error: Error communicating with device no such column:	e-bookuser	Devices	1	07-03-2011 05:09 PM

12-21-2025, 11:23 PM	#2
kovidgoyal creator of calibre Posts: 45,724 Karma: 28549306 Join Date: Oct 2006 Location: Mumbai, India Device: Various	Do not downgrade calibre randomnly, your error message comes from doing that. Updgrade again and it will go away

Advert