Kobo Touch Extended disappears from calibre 5.1

[Phil_C]

calibre 5.1 failed to recognize my Kobo Clara this morning. The Kobo Touch Extended plugin was missing. (The Kobo Touch 2.5.1 was mysteriously disabled.)

Trying to install the Extended driver gave this error:

Spoiler:

calibre, version 5.1.0
ERROR: Install plugin failed: A problem occurred while installing this plugin. This plugin will now be uninstalled. Please post the error message in details below into the forum thread for this plugin and restart calibre.

Traceback (most recent call last):
File "site-packages\calibre\gui2\dialogs\plugin_updater.py", line 731, in _install_clicked
File "site-packages\calibre\customize\ui.py", line 472, in add_plugin
File "site-packages\calibre\customize\ui.py", line 61, in load_plugin
File "site-packages\calibre\customize\zipplugin.py", line 200, in load
File "site-packages\polyglot\builtins.py", line 123, in reload
File "importlib\__init__.py", line 169, in reload
File "<frozen importlib._bootstrap>", line 602, in _exec
File "site-packages\calibre\customize\zipplugin.py", line 184, in load_module
File "calibre_plugins.kobotouch_extended.__init__", line 9, in <module>
ImportError: cannot import name 'KOBOTOUCHEXTENDED' from 'calibre_plugins.kobotouch_extended.device.driver' (<calibre Plugin Loader>)

After a calibre restart, I was able to install the Extended driver and configure it as needed. But calibre could not find the Kobo Clara. So I restarted calibre -- and the Extended plugin once again disappeared.

At this point, I was again unable to install the Extended driver. Another calibre restart. Now I could install it. Another restart and the plugin is gone. And on and on....

I'm on windows 10. Portable calibre 4.23 has no problems. I did not notice any problems with calibre 5.0.

Any ideas? Things to try?

[JSWolf]

There is problem with Calibre 5.1 and the KePub plugins. But there is a solution. Download the 5.1.2 beta that fixes the problem.

https://download.calibre-ebook.com/betas/

[Phil_C]

Originally Posted by JSWolf

There is problem with Calibre 5.1 and the KePub plugins. But there is a solution. Download the 5.1.2 beta that fixes the problem.

https://download.calibre-ebook.com/betas/

That worked. Thank you!

[davidfor]

Calibre version 5.2 has been released. This will fix the problem with the KoboTouchExtended driver and the other Kobo or kepub related plugins. The current released versions of the plugins will work.