boucherguy

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Theme: Quince

Plugins

Akismet
404 Redirect to Home
Classic Editor
Contact Form 7 Extension for Mailchimp
Custom Image CSS Classes
Draw Attention
Duplicate Page and Post
Embed Plus Plugin for Youtube
Envato Market
Essential Grid
Hide Featured Image
Image Hover Effects
iThemes Security
Jetpack
jQuery Pin It Button for Images
MNKY | Theme Core Extend
Popup Maker
Popup Maker Advanced Targeting Conditions
Popup Maker – Exit Intent Popups
Really Simple SSL
ShiftNav
Simple 301 Redirects
Slider Revolution
Smush
SVG Support
UpdraftPlus
WP Logo Showcase
WPBakery Page Builder
Yoast SEO

I have the same issue. Contact form works fine, emails get sent to both parties, and the image also gets sent no problem but I get the same error message. The image gets saved and deleted from the temp folder like normal.

Wordpress Version: 4.9.8
Contact Form 7 Version: 5.0.3

I also have a plugin that I thought could be a problem that disables some writing permissions (iThemese Security) but I disabled that plugin and I still get the error.

Hello,
I had the same issues. My situation was similar. Although I have an SSL with a content delivery network CloudFlare. I dove into the php of the WP Add Custom CSS plugin. If you are able to do this, then this fix worked for me.

Open the file in the plugin folder called “wordpress-add-custom-css.php” this should be in the main folder.

Search for this function (It starts on line 290 and ends at 291)

wp_register_style( 'wp-add-custom-css', $css_base_url . '?display_custom_css=css' );
wp_enqueue_style( 'wp-add-custom-css' );

and then change the value “$css_base_url” to your full base URL like this

wp_register_style( 'wp-add-custom-css', 'https://www.sample.com/' . '?display_custom_css=css' );
wp_enqueue_style( 'wp-add-custom-css' );

This worked for me.

keep in mind if this plugin ever updates this code will be updated again. This worked for me April 30, 2018.