First of all, there are two different types of checks in LO: spell check and grammar check. And normal grammar check is only possible with third-party extensions, since LibreOffice includes just a very basic grammar checker in-built. An example of grammar checker that has an extension for LibreOffice is LanguageTool (and note that any extension may have its dependencies, like Java required for LanguageTool).
For spell check to work, the following must be met:
- A spell checker dictionary for requested language must be installed. LibreOffice includes spell checker dictionaries for multiple languages: for Windows, they are included in the installer (but not all are installed by default: you may control that in Advanced installation mode); for Linux, they are separate packages (e.g., see hunspell-dictionary Ubuntu meta-package listed under recommended packages for libreoffice). Also a spell checker dictionary may be installed as an extension.
- The text in the document must be set to required language. If ru-RU spell checker is installed, and some Russian text is typed, but is marked as, say, Greek, then spell check will not work (in the absence of Greek spell checker dictionary), or will work incorrectly (will mark everything as error when Greek spell checker dictionary is present). The language of the text in document is controlled by many factors: what language is set as default language for documents; if system input language is ignored or not (
Options
▸Language Settings
▸Languages
) - and if not, which system input language and keyboard layout you use; what language is set on Font
tab of character style and paragraph style properties. At any time, language for selection, paragraph, or whole document may be set in Tools
▸Language
menu.
Usually these two requirements are enough. Automatic spell check option controls if the check is performed as you type. Fine tuning of the process is possible in Options
▸Language Settings
▸Writing Aids
.
Grammar check basically has the same requirements (but it uses own dictionaries) - given that you have grammar check extension installed. There are also options for this check under Options
▸Language Settings
, separate for each language (like “English Sentence Checking”).
If it doesn’t work with the above, it means some misconfiguration/corruption of LibreOffice; profile reset or reinstall might be required then.