Hi Anthony,

Check link

Go to line 205 in class-wp.php file and check your function preg_match()

or you can add the folowing code to remove the display of warnings

Hi! I encounter this error before,, you can try this SOLVED! Fix Wordpress Error – Warning: preg_match() [function.preg-match]: Compilation failed: nothing to repeat at offset 1 in [root]/wp-includes/classes.php on line 210 211 | DayDull

godd luck!

All the links now give a 404 error

It appears that you gave up on permalinks and the onsite SEO of using custom permalinks.

The link to a solution in post 4 above was to a solution to a problem created by an obsolete plugin that is not compatible with current wordpress versions.

You can restore SEO friendly permalinks and if you follow these instructions:

Try switching to the Twenty Thirteen theme and then restore permalinks to rule-out a theme-specific issue.

If that does not resolve the issue, try deactivating all plugins. If that resolves the issue, reactivate each one individually until you find the cause.