Title: Error in wpincludes classes.php
Last modified: August 18, 2016

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# Error in wpincludes classes.php

 *  [moazam](https://wordpress.org/support/users/moazam/)
 * (@moazam)
 * [18 years, 6 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/)
 * Hi,
    After upgrading WP to 2.3.1 i am getting this strange error.
 * [29-Nov-2007 22:44:32] PHP Warning: preg_match() [[function.preg-match](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/function.preg-match?output_format=md)]:
   Unknown modifier ‘.’ in /home/site/public_html/wp-includes/classes.php on line
   99
 * [29-Nov-2007 22:44:32] PHP Warning: preg_match() [[function.preg-match](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/function.preg-match?output_format=md)]:
   Unknown modifier ‘.’ in /home/site/public_html/wp-includes/classes.php on line
   100
 * I have disabled all plugins but still getting this error in error_log file
 * This error generates when some one view post file.. I have restored theme to 
   original but nothing happened 🙁
 * Please help!
    Moazam

Viewing 10 replies - 1 through 10 (of 10 total)

 *  [Kafkaesqui](https://wordpress.org/support/users/kafkaesqui/)
 * (@kafkaesqui)
 * [18 years, 6 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660584)
 * “_After upgrading WP to 2.3.1 i am getting this strange error._“
 * Have you tried removing wp-includes/classes.php and re-uploading the copy from
   the installation files? Often an error generated by one of the core files after
   an upgrade means the file did not get updated properly.
 *  Thread Starter [moazam](https://wordpress.org/support/users/moazam/)
 * (@moazam)
 * [18 years, 6 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660689)
 * Yes I did, that too..
 *  Thread Starter [moazam](https://wordpress.org/support/users/moazam/)
 * (@moazam)
 * [18 years, 6 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660692)
 * reinstalled wp, disabled plugins, restored to original theme but still getting
   same problem
 *  [Kafkaesqui](https://wordpress.org/support/users/kafkaesqui/)
 * (@kafkaesqui)
 * [18 years, 6 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660703)
 * Then a look at the underlying code here may help. At those lines in classes.php
   preg_match() is part of the internal rewrites for permalinks. I’m not all that
   adept at working with WordPress’ rewriting scheme, but:
 * What is the permalink structure you are using on the blog? If you reset the structure
   to default (temporarily), does the error remain?
 *  Thread Starter [moazam](https://wordpress.org/support/users/moazam/)
 * (@moazam)
 * [18 years, 6 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660721)
 * I am using custom option and here is it..
    /%category%/%post_id%/%postname%.html
 * everything was working smooth.. before update..
 *  Thread Starter [moazam](https://wordpress.org/support/users/moazam/)
 * (@moazam)
 * [18 years, 6 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660754)
 * I deleted permalinks and changed to default it works.. so it means i can not 
   use the custom permalinks? Please notice this bug
 *  [moshu](https://wordpress.org/support/users/moshu/)
 * (@moshu)
 * [18 years, 5 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660757)
 * This is NOT a bug. I applied exactly the same permalink structure as you posted
   above – and it works. It must be your server or something else interfering with
   it.
 *  Thread Starter [moazam](https://wordpress.org/support/users/moazam/)
 * (@moazam)
 * [18 years, 5 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660762)
 * moshu.. how is it possible all default are working fine but not the custom one?
 *  [moshu](https://wordpress.org/support/users/moshu/)
 * (@moshu)
 * [18 years, 5 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660763)
 * I don’t know. On some servers including the %category% just doesn’t work…
    [Using_Permalinks](http://codex.wordpress.org/Using_Permalinks)
 *  [Kafkaesqui](https://wordpress.org/support/users/kafkaesqui/)
 * (@kafkaesqui)
 * [18 years, 5 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660765)
 * If it *was* working but after your update to 2.3.1 it no longer is, you can certainly
   file a bug report to notify the developers:
 * [http://trac.wordpress.org/](http://trac.wordpress.org/)
 * Be as detailed as possible in reporting it. You might also reference this thread.

Viewing 10 replies - 1 through 10 (of 10 total)

The topic ‘Error in wpincludes classes.php’ is closed to new replies.

## Tags

 * [classes.php](https://wordpress.org/support/topic-tag/classes-php/)

 * In: [Fixing WordPress](https://wordpress.org/support/forum/how-to-and-troubleshooting/)
 * 10 replies
 * 3 participants
 * Last reply from: [Kafkaesqui](https://wordpress.org/support/users/kafkaesqui/)
 * Last activity: [18 years, 5 months ago](https://wordpress.org/support/topic/error-in-wpincludes-classesphp/#post-660765)
 * Status: not resolved

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