Hello,
Since last week, I get a strange error when trying to submit a CF7 form in our testing environment.
Whenever I fill out the form and click the Submit button, the circle spins for a while and then displays the infamous red border error. However, when checking our logs, it shows that the email has indeed been sent successfully, so the red border error is a false negative.
I could probably add a custom filter to change the error message to a “successfully sent” message, but I also have a plugin that creates a PDF with the user input and redirects to a download site for said PDF after successful submission of the form (The plugin is “Send PDF for Contact Form 7”). The redirecting doesn’t work when CF7 outputs a “not sent” error (However, the PDF is still being generated correctly).
After systematically deaktivating my other plugins, I found out that the culprit is the “WP Mail SMTP” plugin that we use to make WordPress send mails via a custom SMTP account. The plugin hasn’t been updated in two months and had not interfered with CF7 in any way until last week.
Deactivating WP Mail SMTP is not an option as the standard wp_mail() function breaks very often.
We run WordPress 4.9.4 with a custom theme (switching to the default twenty fifteen did not solve the issue). CF7 and two additional plugins (Contact Form 7 Conditional Fields, Send PDF for Contact Form 7) are on their latest versions (deactivating those two plugins did not solve the problem either). WP Mail SMTP has been on its latest version for the past two months and did not interfere previously.
When enabling WordPress debugging, the debug log shows no entry related to CF7 or WP Mail SMTP.
I hope that anybody can help me to solve this false red border issue as it breaks out intended functionality.
Regards,
Rafael