New features:
User manual: A new quick reference primer for regular expression syntax https://manual.calibre-ebook.com/regexp_quick_reference.html
Content server: Allow viewing the book metadata while reading a book. In the viewer controls, tap Goto and then Metadata to see the metadata.
Kobo driver: Add support for new firmware.
Bulk metadata edit: Allow choosing the algorithm used for changing the case of titles.
Get books: The koobe.pl store plugin has now become the Swiat Ebookow store plugin.
Allow Copy/paste of book metadata from the main book list. Right click the Edit metadata button to access these actions.
Allow disabling the confirmation popup when opening the containing folder of many books at once.
Bug fixes:
Nook driver: Fix books sent via calibre not appearing under My Files on the Glowlight 3 Plus.
Get Books: Update Mills &; Boon, publio, empik, legimi, woblink and beam-ebooks.de plugins for website changes.
Book polishing: Do not scan book for font usage when subsetting if no embedded fonts are available.
Content server: Open links in the comments section from the book details page in new windows.
Choose English as the User interface language when a locale related environment variable is set to the C locale.
Linux installer: A nicer error message if the user tries to run the installer on an ARM machine.
New news sources:
El Cohete a la luna by Darko Miletic.
Improved news sources:
Boston Globe.
The Times.
Economist.