Title: Unknown modifier warnings Last modified: September 8, 2023 --- # Unknown modifier warnings * Resolved [yurchik1](https://wordpress.org/support/users/yurchik1/) * (@yurchik1) * [2 years, 9 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/) * Good day, * I’ve been using the UpdraftPlus plugin for a while and enjoying it. Recently, I’ve encountered a high CPU usage, so I am logging everything I can. During the backup I was full of these notifications: * ```wp-block-code Warning: preg_match(): Unknown modifier '/' in /home/avtomigc/public_html/wp-content/plugins/updraftplus/includes/class-filesystem-functions.php on line 195 Warning: preg_match(): Unknown modifier '/' in /home/avtomigc/public_html/wp-content/plugins/updraftplus/includes/class-filesystem-functions.php on line 203 ``` * These two warnings were being repeated like hundreds of times during the backup. Is there my mistake standing behind that, I’d like to get rid of those for I probably will have more logs to read and don’t want the file to be enlarged be hundreds of these ones. * Really appreciate your time, * with all due respect, * Yuryi - This topic was modified 2 years, 9 months ago by [yurchik1](https://wordpress.org/support/users/yurchik1/). Viewing 15 replies - 1 through 15 (of 24 total) 1 [2](https://wordpress.org/support/topic/unknown-modifier-warnings/page/2/?output_format=md) [→](https://wordpress.org/support/topic/unknown-modifier-warnings/page/2/?output_format=md) * Plugin Contributor [bcrodua](https://wordpress.org/support/users/bcrodua/) * (@bcrodua) * [2 years, 9 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17036302) * Hi, * UpdraftPlus has been designed to be dependent on your server resources to run backups and other processes. To reduce the resource usage, please check this FAQ: [https://updraftplus.com/faqs/how-much-resources-does-updraftplus-need/](https://updraftplus.com/faqs/how-much-resources-does-updraftplus-need/) * Thanks, Bryle * Thread Starter [yurchik1](https://wordpress.org/support/users/yurchik1/) * (@yurchik1) * [2 years, 9 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17036332) * Thank you so much for the answer [@bcrodua](https://wordpress.org/support/users/bcrodua/)! I’m not saying Updraft is a reason of my high CPU usage. I’m just trying to get rid of any errors that might cause problems with it. These lines don’t seem to be stating about resources overuse, but I’d still like to have them removed. * Thread Starter [yurchik1](https://wordpress.org/support/users/yurchik1/) * (@yurchik1) * [2 years, 9 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17037928) * UPD. This may happen a couple times a day and do not depend on the process of backup (for instance, today it happened at 4 a.m. and at 4 p.m.). * Plugin Author [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/) * (@davidanderson) * [2 years, 9 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17038203) * What is the name of your site in your admin dashboard in Settings -> General? * Thread Starter [yurchik1](https://wordpress.org/support/users/yurchik1/) * (@yurchik1) * [2 years, 9 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17038206) * [@davidanderson](https://wordpress.org/support/users/davidanderson/) it’s in Ukrainian: АвтоМить * Plugin Author [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/) * (@davidanderson) * [2 years, 9 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17038209) * Thank you. Can you give me an example name of one of your backup files? i.e. The full filename of a file that UD is creating. The PHP coding messages (which indeed aren’t related to resource usage one way or the other) indicate that there’s something unexpected. * Thread Starter [yurchik1](https://wordpress.org/support/users/yurchik1/) * (@yurchik1) * [2 years, 9 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17038223) * [@davidanderson](https://wordpress.org/support/users/davidanderson/) Sure! One of the updraft backup files name (they are stored in my GoogleDrive): * ```wp-block-code backup_2023-09-08-1150_avtomigcomua_eb1d0dc368fe-others.zip ``` * The warning messages in `/home/avtomigc/eror_log.txt`(repeatedly; exactly 56 times, two times today i.e. two batches of 56 pairs): * ```wp-block-code [09-Sep-2023 01:00:18 UTC] PHP Warning: preg_match(): Unknown modifier '/' in /home/avtomigc/public_html/wp-content/plugins/updraftplus/includes/class-filesystem-functions.php on line 195 [09-Sep-2023 01:00:18 UTC] PHP Warning: preg_match(): Unknown modifier '/' in /home/avtomigc/public_html/wp-content/plugins/updraftplus/includes/class-filesystem-functions.php on line 203 ``` - This reply was modified 2 years, 9 months ago by [yurchik1](https://wordpress.org/support/users/yurchik1/). * Plugin Author [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/) * (@davidanderson) * [2 years, 9 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17045854) * The PHP warnings you’re seeing ought also to be logged in the UpdraftPlus log file (assuming that they are logged whilst taking a backup). Do they appear there? Can you include the surrounding lines from the UpdraftPlus log file? That will help me to understand the circumstances when this occurs. (In my own testing I’ve not been able to replicate this yet). * Thread Starter [yurchik1](https://wordpress.org/support/users/yurchik1/) * (@yurchik1) * [2 years, 8 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17046467) * Thank you for your efforts once again, [@davidanderson](https://wordpress.org/support/users/davidanderson/)! Having gathered some statistics for this time I can tell it happens exactly every 12 hours and diverges with the schedule of backups (that are not set to be happening that frequently also). Additionally, I’ve made sure backup logs do not contain any of these errors. Here are some timestamps of these batches: `[08-Sep-2023 01:00:18 UTC][08-Sep-2023 13:00:19 UTC][09-Sep-2023 01:00:18 UTC][09-Sep-2023 13:00:10 UTC][10-Sep-2023 01:00:12 UTC][10-Sep-2023 13:00:27 UTC][11-Sep-2023 01:00:14 UTC][11-Sep-2023 13:00:14 UTC]... * I’m also trying to correct as many errors as I can, getting rid off unused plugins, writing my own code instead, assuming that’s a conflict, but no luck with the errors so far 🙁 * UPD. Today, during the wp-cron (configure to run every hour) I got this. Seems it’s also related to updraft and this happened during the Updraft database backup: * ```wp-block-code Can't locate cPstrict.pm in @INC (you may need to install the cPstrict module) (@INC contains: /usr/local/cpanel /usr/local/cpanel /usr/local/cpanel/3rdparty/perl/536/cpanel-lib/x86_64-linux /usr/local/cpanel/3rdparty/perl/536/cpanel-lib /usr/local/cpanel/3rdparty/perl/536/lib/x86_64-linux /usr/local/cpanel/3rdparty/perl/536/lib /opt/cpanel/perl5/536/site_lib/x86_64-linux /opt/cpanel/perl5/536/site_lib) at /usr/local/cpanel/Cpanel/Math/Bytes.pm line 8. BEGIN failed--compilation aborted at /usr/local/cpanel/Cpanel/Math/Bytes.pm line 8. Compilation failed in require at /usr/local/cpanel/Cpanel/Quota.pm line 18. BEGIN failed--compilation aborted at /usr/local/cpanel/Cpanel/Quota.pm line 18. Compilation failed in require at /home/avtomigc/public_html/wp-content/plugins/updraftplus/includes/get-cpanel-quota-usage.pl line 9. BEGIN failed--compilation aborted at /home/avtomigc/public_html/wp-content/plugins/updraftplus/includes/get-cpanel-quota-usage.pl line 9. ``` - This reply was modified 2 years, 8 months ago by [yurchik1](https://wordpress.org/support/users/yurchik1/). * Plugin Author [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/) * (@davidanderson) * [2 years, 8 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17051496) * Hi, * Since you’re a coder, you could add this just before the lines that are logging the PHP warnings: * ```wp-block-code error_log(serialize($match).", backtrace: ".wp_debug_backtrace_summary()); ``` * That will then mean that before the warnings are logged, it also logs the path through the code to get there, and the value that there’s a problem with. * For the cPanel message, that just means that UD wasn’t able to ask cPanel what your disk quota was. You can disable that check entirely with this in your `wp- config.php`: * `define('UPDRAFTPLUS_SKIP_**CPANEL**_QUOTA_CHECK', true);` * David * Thread Starter [yurchik1](https://wordpress.org/support/users/yurchik1/) * (@yurchik1) * [2 years, 8 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17051706) * Hi [@davidanderson](https://wordpress.org/support/users/davidanderson/) , * Excuse me, I’m a bit confused. The errors are generated by WordPress due to the errors in the plugin’s PHP code. I can’t simply find the error_log() that logs this and add something before it. * Unless I got you wrong, may be you meant to add the * ```wp-block-code error_log(serialize($match).", backtrace: ".wp_debug_backtrace_summary()); ``` * line before the lines in the plugin that cause the issue? I added it right before the problematic lines (195 and 203) in `updraftplus/includes/class-filesystem- functions.php` and am going to wait until the error triggers again. Am I doing everything right? * And thank you for the addressing cpanel issue immediately, I will try that! * Plugin Author [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/) * (@davidanderson) * [2 years, 8 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17051747) * You have done the thing my message said to do. * Thread Starter [yurchik1](https://wordpress.org/support/users/yurchik1/) * (@yurchik1) * [2 years, 8 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17052681) * Hey, [@davidanderson](https://wordpress.org/support/users/davidanderson/) ! * I’ve inspected logs now and got the results. Now, the pairs look like this: * ```wp-block-code [15-Sep-2023 00:30:12 UTC] s:22:"https://avtomig.com.ua";, backtrace: do_action_ref_array('updraftplus_clean_temporary_files'), WP_Hook->do_action, WP_Hook->apply_filters, UpdraftPlus_Filesystem_Functions::clean_temporary_files [15-Sep-2023 00:30:12 UTC] PHP Warning: preg_match(): Unknown modifier '/' in /home/avtomigc/public_html/wp-content/plugins/updraftplus/includes/class-filesystem-functions.php on line 196 [15-Sep-2023 00:30:12 UTC] s:22:"https://avtomig.com.ua";, backtrace: do_action_ref_array('updraftplus_clean_temporary_files'), WP_Hook->do_action, WP_Hook->apply_filters, UpdraftPlus_Filesystem_Functions::clean_temporary_files [15-Sep-2023 00:30:12 UTC] PHP Warning: preg_match(): Unknown modifier '/' in /home/avtomigc/public_html/wp-content/plugins/updraftplus/includes/class-filesystem-functions.php on line 206 ``` * Plugin Author [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/) * (@davidanderson) * [2 years, 8 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17053520) * This indicates that somehow in your scheduled task list on your site, a parameter is being sent to the twice-daily clean-up task. I can’t reproduce that on a test site (in the code there’s no apparent way it could happen). So it suggests that somehow the scheduled task list in your WP install has become corrupted. If you install the free plugin “WP Crontrol”, and go to the task list under the “Tools” menu, what does it show for the `updraftplus_clean_temporary_files` task? * Thread Starter [yurchik1](https://wordpress.org/support/users/yurchik1/) * (@yurchik1) * [2 years, 8 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/#post-17053597) * I see. Due to the high CPU usage, I had disabled wp-cron and added a scheduled task via cpanel (twice an hour). I hope there’s nothing wrong with that. * In the “WP Crontrol” plugin it looks like this: * > [View post on imgur.com](https://imgur.com/a/eFUyJMF) * P.S. I attached the label with translation for the Ukrainian part on the image. Viewing 15 replies - 1 through 15 (of 24 total) 1 [2](https://wordpress.org/support/topic/unknown-modifier-warnings/page/2/?output_format=md) [→](https://wordpress.org/support/topic/unknown-modifier-warnings/page/2/?output_format=md) The topic ‘Unknown modifier warnings’ is closed to new replies. * ![](https://ps.w.org/updraftplus/assets/icon-256x256.jpg?rev=1686200) * [UpdraftPlus: WP Backup & Migration Plugin](https://wordpress.org/plugins/updraftplus/) * [Frequently Asked Questions](https://wordpress.org/plugins/updraftplus/#faq) * [Support Threads](https://wordpress.org/support/plugin/updraftplus/) * [Active Topics](https://wordpress.org/support/plugin/updraftplus/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/updraftplus/unresolved/) * [Reviews](https://wordpress.org/support/plugin/updraftplus/reviews/) * 24 replies * 3 participants * Last reply from: [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/) * Last activity: [2 years, 8 months ago](https://wordpress.org/support/topic/unknown-modifier-warnings/page/2/#post-17090797) * Status: resolved