Lightroom Tip: Automatically Replace Empty Spaces and Illegal Characters in File Name
There is a handy option in Lightroom Preferences (Edit > Preferences on Windos machine or Lightrom > Preferences on Mac) to avoid empty spaces in file names. When instructed, Lightroom will replace the empty space with dash or underscore, whatever you choose in Preferences > File Handling > File Name Generation. There is also option just above When a file has a empty space, to instruct Lightroom what to do with illegal characters which you may type from time to time (nobody's perfect).
If you are wondering what is a benefit and why I am writing all this, here is short explanation: you will avoid error messages when exporting files and extremely ugly and inconvenient %20 (automatic replacement for empty space in file name) when posting images on the Web.