How to find and replace empty cells in Libre Office Calc

To find and replace (CTRL + H) empty cells in Libre Office Calc you can use a regular expressions (also called "Finds an empty paragraph" in context of a spreadsheet):

It is also possible to just enter a regular expression in the search (CTRL + F), but there is no option to only search in the current selection like in the screenshot above. Use find and replace instead if needed.