Hi, maybe you prune old threads frequently on Your vBUlletin forum and you wish to redirect google and this threads visitors to forum homepage.
How to do it?
Someone adviced to add "ErrorDocument 404 /index.php" into .htaccess file, but this dont works for me..
But you can also edit default message "Invalid Thread specified. If you followed a valid link, please notify the administrator"
To do it, login to vbulletin forum administration > Languages & Phrases > Search in Phrases > add "If you followed a valid" phrasse into "Search for Text" field, click into "Phrase Type" field and do Ctrl+A keyboard shortcut to select all. Then in "Search in ..." select "Phrase Text and Phrase Variable Name" and hit "Find" button. Then you might be able to edit that default message.