Calibre: error communicating with device, failed to find obfuscation key is due to encrypted fonts. Calibre’s KoboTouchExtended plugin was unable to locate the key to decrypt the embedded fonts to convert the EPUB file to KEPUB.
The full error message goes like this:
ERROR: Error: Error communicating with device
Failed to find obfuscation key
Traceback (most recent call last):
File "site-packages\calibre\gui2\device.py", line 89, in run
File "site-packages\calibre\gui2\device.py", line 593, in _upload_books
File "calibre_plugins.kobotouch_extended.device.driver", line 399, in upload_books
File "site-packages\calibre\devices\kobo\driver.py", line 2087, in upload_books
File "calibre_plugins.kobotouch_extended.device.driver", line 206, in _modify_epub
File "site-packages\calibre\ebooks\oeb\polish\container.py", line 1184, in __init__
File "site-packages\calibre\ebooks\oeb\polish\container.py", line 1301, in process_encryption
ObfuscationKeyMissing: Failed to find obfuscation keyTo fix this “missing obfuscation key” issue is quite simple, convert from EPUB to EPUB and resend to the device.
Alternatively, you can just keep the book in its original EPUB format.