[jackie_w]

Originally Posted by davidfor

I think I might have broken something in the migration of the old settings. I didn't recheck this last night and was working with an already migrated settings file. Could you removed the file "device_drivers_KOBOTOUCH.py" in your calibre configuration directory and try again?

I did as you asked. In case it's relevant, before starting I also removed from my config directory:
- device_drivers_KOBO.py
- device_drivers_KOBOTOUCHCSSEDIT.py (the driver for my subclassed KOBOTOUCH)

I'm still getting an error. This is the complete log from calibre startup to failing to save the config:

Spoiler:

*** Hello, Jackie! ***
Running calibre from source [C:\JS_git_devel\cal\src]

calibre 2.57.1* [64bit]  embedded-python: True is64bit: True
Windows-7-6.1.7601-SP1 Windows ('64bit', 'WindowsPE')
('Windows', '7', '6.1.7601')
Python 2.7.9
Windows: ('7', '6.1.7601', 'SP1', 'Multiprocessor Free')
Successfully initialized third party plugins: DeDRM && DOC Input && Obok DeDRM && Goodreads && KoboBooks && Diaps Editing Toolbag && JS Mod Epub && JSTest Plugin && KePub Input && Modify ePub && Open With && KePub Output && KindleUnpack - The Plugin && Barnes & Noble && Extract ISBN && KePub Metadata Reader && Epub2Kepub && Wiki Reader && ScrambleEbook && Kobo Utilities && Quality Check && Search The Internet && Fantastic Fiction && EpubSplit && KePub Metadata Writer && Count Pages && Copy Cover To Device
Starting up...
DEBUG:    0.0 obok::utilities.py - loading translations
DEBUG:    0.0 obok::dialogs.py - loading translations
DEBUG:    0.0 obok::config.py - loading translations
DEBUG:    0.0 obok::action_err.py - loading translations
cssutils 1.0
lxml etree: 3.3.5
cssutils 1.0
lxml etree: 3.3.5
DEBUG:    0.0 KoboUtilites::action.py - loading translations
DEBUG:    0.0 KoboUtilites::dialogs.py - loading translations
DEBUG:    0.0 KoboUtilites::action.py - loading translations
DEBUG:    2.5 No Kobo Touch, Glo or Mini appears to be connected
DEBUG:    2.5 rebuild_menus - self.supports_ratings=None, self.supports_tiles=None
DEBUG:    2.5 KoboUtilities:set_toolbar_button_tooltip - start: text='None'
DEBUG:    2.5 device_driver_name - could not load extended driver. Exception= No module named kobotouch_extended.device.driver
DEBUG:    2.5 KoboUtilities:set_toolbar_button_tooltip - setting to text='Utilities to use with Kobo ereaders

Driver: KoboTouch'
Started up in 3.52 seconds with 106 books
SMART_DEV (   0.00:  0.004) _attach_to_port try ip address "" on port 9090

*** Hello, Jackie! ***
Running calibre from source [C:\JS_git_devel\cal\src]

SMART_DEV (   1.15:  1.040) startup_on_demand listening on port 9090
SMART_DEV (   1.16:  0.001) _attach_to_port try ip address "" on port 54982
SMART_DEV (   1.17:  0.001) startup_on_demand broadcast socket listening on port 54982
SMART_DEV (   2.20:  1.018) run All IP addresses {'{72227828-5A67-43D2-BFE6-7620F3F56F3D}': [{'broadcast': '192.168.0.255', 'addr': '192.168.0.12', 'netmask': '255.255.255.0'}], '{846EE342-7039-11DE-9D20-806E6F6E6963}': [{'broadcast': '127.255.255.255', 'addr': '127.0.0.1', 'netmask': '255.0.0.0'}], '{B3138E13-B2C6-4260-999A-B513AFDE71DA}': [{'addr': '169.254.48.54'}], '{5EF38EB0-33CB-4B37-9C73-E74F94812551}': [{'addr': '169.254.156.58'}]}
DEBUG:    0.0 ExtraCustomization.__init__ - extra_customization_message= []
DEBUG:    0.0 ExtraCustomization.__init__ - extra_customization_choices= None
DEBUG:    0.0 ExtraCustomization.__init__ - device_settings.extra_customization= []
DEBUG:    0.0 ExtraCustomization.__init__ - device_settings= <calibre.utils.config_base.OptionValues object at 0x000000001268CB00>
DEBUG:    0.0 ExtraCustomization::has_extra_customizations - self.extra_customization_message []
DEBUG:   39.3 KOBOTOUCHConfig::commit: start
DEBUG:   39.3 TabbedDeviceConfig::commit: start
DEBUG:   39.4 commit: starting setting=<calibre.utils.config_base.ConfigProxy object at 0x000000001268CA58>
DEBUG:   39.4 commit: self.formats.format_map= [u'kepub', u'epub', u'pdf', u'txt', u'cbz', u'cbr']
DEBUG:   39.4 KoboTouch::migrate_old_settings - start
calibre 2.57.1* [64bit]  embedded-python: True is64bit: True
Windows-7-6.1.7601-SP1 Windows ('64bit', 'WindowsPE')
('Windows', '7', '6.1.7601')
Python 2.7.9
Windows: ('7', '6.1.7601', 'SP1', 'Multiprocessor Free')
Successfully initialized third party plugins: DeDRM && DOC Input && Obok DeDRM && Goodreads && KoboBooks && Diaps Editing Toolbag && JS Mod Epub && JSTest Plugin && KePub Input && Modify ePub && Open With && KePub Output && KindleUnpack - The Plugin && Barnes & Noble && Extract ISBN && KePub Metadata Reader && Epub2Kepub && Wiki Reader && ScrambleEbook && Kobo Utilities && Quality Check && Search The Internet && Fantastic Fiction && EpubSplit && KePub Metadata Writer && Count Pages && Copy Cover To Device
Traceback (most recent call last):
  File "C:\JS_git_devel\cal\src\calibre\gui2\preferences\plugins.py", line 292, in customize_plugin
  File "C:\JS_git_devel\cal\src\calibre\gui2\preferences\plugins.py", line 370, in modify_plugin
  File "C:\JS_git_devel\cal\src\calibre\customize\__init__.py", line 173, in do_user_config
  File "C:\JS_git_devel\cal\src\calibre\devices\kobo\driver.py", line 2790, in save_settings
  File "C:\JS_git_devel\cal\src\calibre\devices\kobo\kobotouch_config.py", line 99, in commit
  File "C:\JS_git_devel\cal\src\calibre\gui2\device_drivers\tabbed_device_config.py", line 224, in commit
  File "C:\JS_git_devel\cal\src\calibre\devices\kobo\driver.py", line 165, in prefs
  File "C:\JS_git_devel\cal\src\calibre\utils\config.py", line 408, in __setitem__
  File "C:\JS_git_devel\cal\src\calibre\utils\config.py", line 353, in commit
  File "C:\JS_git_devel\cal\src\calibre\utils\config.py", line 392, in to_raw
  File "json\__init__.py", line 250, in dumps
  File "json\encoder.py", line 209, in encode
  File "json\encoder.py", line 434, in _iterencode
  File "json\encoder.py", line 408, in _iterencode_dict
  File "json\encoder.py", line 442, in _iterencode
  File "C:\JS_git_devel\cal\src\calibre\utils\config.py", line 373, in to_json
TypeError: <calibre.utils.config_base.OptionValues object at 0x00000000090AA320> is not JSON serializable

Is there something else I should have disabled or deleted before starting?

ETA: Just in case removing device_drivers_KOBO.py wasn't a very smart thing to do, I put it back, restarted calibre and re-ran the test. Still the same error

TypeError: <calibre.utils.config_base.OptionValues object at 0x...> is not JSON serializable

ETA2: I've just thought of something else. When I tried your original Tabbed Config (May 18) I don't think I even attempted to save the config. So it's quite possible that, whatever the problem is today, it also existed then.