Learn how to fix the preg_match WordPress Error from our experts. Our WordPress Support team is here to help you with your questions and concerns.

preg_match WordPress Error | Resolved

Some of our customers have recently been running into the following error while editing articles in WordPress.

Warning: preg_match() [function.preg-match]: Compilation failed: nothing to repeat at offset 1 in [yoursite]/wp-includes/classes.php on line 210
Warning: preg_match() [function.preg-match]: Compilation failed: nothing to repeat at offset 1 in [yoursite]/wp-includes/classes.php on line 211

In some cases, they also came across the following error:

Warning: Cannot modify header information – headers already sent by (output started at [yoursite]/wp-includes/classes.php:210) in [yoursite]/wp-includes/pluggable.php on line 240

Fortunately, our experts have a solution for these errors.

Interestingly, this error is due to corruption in the permalink structure. The error messages make it clear that the errors are related to lines 210 and 211 in classes.php which deal with permalink searching and matching.

Let’s take a look at how to resolve the error:

1. First, we have to disable all the plugins in WordPress.
2. After that, we must head to the WordPress Permalinks settings under the Settings header in the admin dashboard.
3. Then, switch to the first default setting, which is for %post_id% only.
4. Next, we have to save the settings and verify the site is now working.
5. Once the site is working, we have to switch back to the custom permalinks setting.
6. Finally, we can enable the plugins one by one and check for errors.

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Conclusion

In summary, our Support Techs demonstrated how to resolve the preg_match WordPress Error with just a few steps.