wpsnoop: fix Contact Form by ContactUs plugin conflicts, errors & issues
When the plugin Contact Form by ContactUs conflicts or throws a PHP error we hope wpsnoop can help you to fix the issue quickly.
Discover which shortcodes wp-options PHP functions database tables and files are created by Contact Form by ContactUs, plus learn which plugins and/or themes could be in conflict with Contact Form by ContactUs.
Troubleshooting theme and plugin conflicts is easier when you know what Contact Form by ContactUs leaves behind after uninstalling it from a WordPress installation, there is a list down below for your convenience.
Expert advice is recommended if you are not technically proficient with PHP, MySQL etc. View support options for Contact Form by ContactUs
Get professional support for Contact Form by ContactUs here
When you need professional help with WordPress: get help here
What does Contact Form by ContactUs version 4.2.5 add to WordPress? Answers Here.
This is an automatically generated report - it is possible for Contact Form by ContactUs to perform differently in your installation, previous versions before 4.2.5 may have created a different set of shortcodes, used different function names or could have created entirely different database tables to store settings and operate. This is not an exhaustive list but shows how version 4.2.5 of Contact Form by ContactUs behaves when installed and removed on a clean installation of WordPress.
We have not tested individual shortcodes, features or settings of this plugin but instead have concentrated on the potential for obvious errors and conflicts which can occur, if you need help with the plugin in your local installation you can get WordPress help and support for Contact Form by ContactUs by clicking here.
Our testing covered the free version of this plugin there may or may not be a paid version or premium version available for purchase that unlocks additional features and could behave in a slightly or very different manner.
Summary of WordPress plugin analysis: Contact Form by ContactUs
Plugin Slug: export-all-users-to-csv
Internal ID: 25523
Addon Type: Plugin
Version: 4.2.5
Price:
Free
Source: WordPress.org
Files: 133 (1.17MB)
Short Codes: [ / ] 1
Database Tables: 0
Function Count: 35
Code Review: Search Provit
Which new files does Contact Form by ContactUs add to WordPress?
This section will populate with a table showing an icon, size and filepath.
The plugin Contact Form by ContactUs added 133 new files when it was installed with WP-CLI in our WordPress test environment.
| Type & Path | Size | Conflicts |
|---|---|---|
| wp-content/plugins/export-all-users-to-csv/ | 1.17MB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/contactus_form_ajx_request.php | 28.31kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/contactus_form_functions.php | 16.76kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/contactus_form_widget.php | 1.47kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/contactus_form.php | 169.39kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/index.php | 232.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/libs/ | 26.24kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/libs/cusAPI.class.php | 26.24kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/readme.txt | 30.40kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/ | 239.15kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/ | 106.08kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/images/ | 11.12kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/images/bx_loader.gif | 8.38kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/images/controls.png | 2.74kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/jquery.bxslider.css | 3.52kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/jquery.bxslider.js | 48.13kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/jquery.bxslider.min.js | 18.67kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/plugins/ | 10.70kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/plugins/jquery.easing.1.3.js | 7.91kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/plugins/jquery.fitvids.js | 2.80kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/bxslider/readme.md | 13.92kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/colorbox/ | 54.77kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/colorbox/colorbox.css | 4.27kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/colorbox/images/ | 12.47kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/colorbox/images/border.png | 112.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/colorbox/images/controls.png | 2.83kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/colorbox/images/loading_background.png | 157.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/colorbox/images/loading.gif | 9.21kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/colorbox/images/overlay.png | 182.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/colorbox/jquery.colorbox-min.js | 10.83kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/colorbox/README.md | 27.19kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/cUsCF_cats_module.js | 2.91kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/cUsCF_scripts.js | 47.47kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/introjs/ | 27.92kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/introjs/intro.min.js | 12.91kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/introjs/introjs.config.js | 9.39kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/scripts/introjs/introjs.min.css | 5.62kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/ | 689.09kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/cUsCF_style.css | 64.91kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ | 624.19kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/account.png | 2.95kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ajax-loader.gif | 847.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/arrow_state_grey_right.png | 202.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/bg.jpg | 8.15kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/check.png | 537.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/close.gif | 140.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/contact-us-what-you-get_03.jpg | 21.76kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/contactus-logo.png | 3.88kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/contactus-users.png | 5.01kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cu-chat-m.png | 2.09kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cu-facebook-m.png | 1.27kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cu-googleplus-m.png | 2.19kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cu-help-m.png | 2.25kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cu-linkedin-m.png | 1.84kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cu-twitter-m.png | 1.90kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cu-youtube-m.png | 2.17kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cUsCF_do.png | 62.22kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cUsCF_header_bk.jpg | 4.34kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cUsCF_no_button.png | 1.20kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/cUsCF_yes_button.png | 1.21kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/d_reports_b.png | 366.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/d_reports.png | 968.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/def_template.png | 1.78kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/empty.png | 1.08kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/facebook_link.png | 2.19kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/favicon.gif | 1.26kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/five_stars.png | 1.22kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/footer-logo.png | 2.96kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/form_tools_Ab.png | 1.36kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/form_tools_cf_new.png | 4.15kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/form_tools_cf.png | 1.98kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/form_tools_confF.png | 1.43kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/form_tools_ctab.png | 1.38kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/form_type_af.png | 2.14kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/form_type_cf.png | 1.92kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/form_type_df.png | 1.95kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/form_type_nl.png | 2.10kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/formsettings_zoom_bk.png | 976.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/formsettings_zoom.png | 2.23kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/getting_bullet.png | 1.66kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/gotodashboard_button.png | 2.94kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/h3_custom.png | 1.70kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/h3_premium.png | 1.44kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/header-logo.png | 2.85kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/intro_000.png | 47.24kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/intro_001.png | 10.79kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/intro_003.png | 66.86kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/intro_004.png | 42.00kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/intro_ac_000.png | 7.83kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/intro_fp_000.png | 4.19kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/intro_sc_000.png | 3.10kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/intro_set_000.png | 3.41kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/linkedin_link.png | 2.01kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/loading.gif | 10.57kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/next.png | 1.50kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/pmessage_bullet.png | 1.26kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/prev.png | 1.54kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/selectable_dis_button.png | 1.13kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/selectable_en_button.png | 1.18kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/status_yellow.png | 1.12kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/tick.png | 332.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/twitter_link.png | 2.04kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-bg_diagonals-thick_18_b81900_40x40.png | 470.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-bg_diagonals-thick_20_666666_40x40.png | 366.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-bg_flat_10_000000_40x100.png | 257.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-bg_glass_100_f6f6f6_1x400.png | 315.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-bg_glass_100_fdf5ce_1x400.png | 400.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-bg_glass_65_ffffff_1x400.png | 259.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-bg_gloss-wave_35_f6a828_500x100.png | 5.73kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-bg_highlight-soft_100_eeeeee_1x100.png | 332.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-bg_highlight-soft_75_ffe45c_1x100.png | 380.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-icons_222222_256x240.png | 6.62kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-icons_ef8c08_256x240.png | 4.25kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/ui-icons_ffd27a_256x240.png | 4.25kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/upgrade-banner-admin.png | 24.52kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/video_icon_16.png | 1.11kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/video_icon.png | 1.45kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_bk.jpg | 21.76kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_road.png | 32.06kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_01_contacts.png | 9.75kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_02_contactform.png | 10.05kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_03_wp.png | 10.23kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_04_call.png | 9.31kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_05_alerts.png | 9.15kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_06_ab.png | 8.65kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_07_3rd.png | 10.91kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_08_chat.png | 14.61kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_09_loadforms.png | 9.83kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_10_analytics.png | 8.34kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_11_customizable.png | 11.22kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_cloud.png | 24.35kB | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start_title_bk.png | 925.00B | No known conflicts with other themes or plugins. |
| wp-content/plugins/export-all-users-to-csv/style/images/what_you_get_start.png | 4.26kB | No known conflicts with other themes or plugins. |
Which new shortcodes does Contact Form by ContactUs add to WordPress?
The plugin Contact Form by ContactUs added 1 new shortcode when it was installed with WP-CLI in our WordPress test environment.
| ShortCode | Known Plugin or Theme conflicts | |
|---|---|---|
| [show-contactus.com-form] | The show-contactus.com-form shortcode has potential conflicts with at least 2 other plugins or themes. |
Note: We have not yet checked to see if these shortcodes work as expected in pages, posts, sidebar widgets, or when set as the page title, in content, in the excert, in menus or anywhere else within a WordPress installation. A shortcode could produce errors due to parameters added when it is used, or if the plugin is updated and the format of the shortcode has changed.
Which new database tables are created by the WordPress plugin Contact Form by ContactUs?
Contact Form by ContactUs did not create any new database tables when it was installed. It is possible that the plugin creates new database tables after an initial setup or configuration or after some period of use.
Which new options are added to the wp-options table by Contact Form by ContactUs?
When Contact Form by ContactUs was activated and loaded for the first time it created 1 new option in the wp_options table. Any known conflicts will be shown in red.
| Option Name | Known Conflicts | |
|---|---|---|
| widget_contactus_form_widget | Potential conflict with 2 plugins or themes | |
During use Contact Form by ContactUs may or may not create more options depending on how the plugin is configured and depending on which other themes and plugins are active in your specific hosting environment.
After disabling and deleting Contact Form by ContactUs there were 2 options still present in the wp-options table:
Contact Contact Form by ContactUs experts for help
What new PHP functions does Contact Form by ContactUs declare when it is active?
Installing Contact Form by ContactUs added 35 new function to Wordpress at run-time. These functions are internal and generally aren't meant to be used except by developpers who wish to interface with the plugin to enhance or alter its behavior.
Using Contact Form by ContactUs from the command line with WP-CLI
The following commands are provided for convenience and should only be used if you understand how WP-CLI works. These commands refer to a single WordPress instance and may need to be modified if you are working with a Multisite installation.
How to install Contact Form by ContactUs from the command line with WP-CLI
Navigate to the root of your WordPress installation and type the following command:
wp plugin install export-all-users-to-csv
How to activate Contact Form by ContactUs from the command line with WP-CLI
To immediately activate Contact Form by ContactUs after WP-CLI downloads the latest version you can use the following command:
wp plugin install export-all-users-to-csv --activate
How to reinstall Contact Form by ContactUs from the command line with WP-CLI
To force a reinstallation of Contact Form by ContactUs which overwrites the current plugin without asking for confirmation you can use the following command:
wp plugin install export-all-users-to-csv --force
How to update Contact Form by ContactUs to the latest version from the command line with WP-CLI
wp plugin update export-all-users-to-csv
How to delete Contact Form by ContactUs from the command line with WP-CLI
wp plugin delete export-all-users-to-csv
Where can you download earlier versions of Contact Form by ContactUs?
Whenever possible you should use the latest version of plugins and themes, however if you have recently updated and discovered that you need to install an earlier version you may be able to download other versions of Contact Form by ContactUs from the WordPress repository by visiting this link.
Please note that installing earlier versions of a theme or plugin is not generally a recommended course of action for most users and could re-introduce security, stability or other issues in Contact Form by ContactUs
About our testing enviroment
Tests were conducted using Apache 2.4.29, PHP 7.2 on Ubuntu 18.04, MySQL 5.7.33 and WordPress 5.9
It is very possible that different versions of PHP such as PHP 8.0, PHP 7.4, or PHP 7.3 could behave differently with Contact Form by ContactUs. Different versions of WordPress could implement the features of this plugin in slightly different ways as well.