Title: Errors using MailOptin Last modified: May 21, 2019 --- # Errors using MailOptin * Resolved [cscales](https://wordpress.org/support/users/cscales/) * (@cscales) * [7 years ago](https://wordpress.org/support/topic/errors-using-mailoptin/) * Hi, I’m getting error messages using MailOptin that are being displayed on the pages that I use with Elementor’s forms. Is there a solution to this? * Here are the error messages: * Deprecated: define(): Declaration of case-insensitive constants is deprecated in /home/learnc20/public_html/wp-content/plugins/mailoptin/mailoptin.php on line 19 * Notice: Undefined index: mailchimp_api_key in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/MailChimpConnect/AbstractMailChimpConnect.php on line 37 * Notice: Undefined index: drip_api_token in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/DripConnect/AbstractDripConnect.php on line 35 * Notice: Undefined index: drip_account_id in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/DripConnect/AbstractDripConnect.php on line 36 * Notice: Undefined index: sendlane_api_key in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/SendlaneConnect/AbstractSendlaneConnect.php on line 35 * Notice: Undefined index: sendlane_hash_key in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/SendlaneConnect/AbstractSendlaneConnect.php on line 36 * Notice: Undefined index: sendlane_domain in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/SendlaneConnect/AbstractSendlaneConnect.php on line 37 * Notice: Undefined index: convertkit_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/ConvertKitConnect/AbstractConvertKitConnect. php on line 33 * Notice: Undefined index: activecampaign_api_url in /home/learnc20/public_html/ wp-content/plugins/mailoptin/src/connections/ActiveCampaignConnect/AbstractActiveCampaignConnect. php on line 33 * Notice: Undefined index: activecampaign_api_key in /home/learnc20/public_html/ wp-content/plugins/mailoptin/src/connections/ActiveCampaignConnect/AbstractActiveCampaignConnect. php on line 34 * Notice: Undefined index: mailerlite_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/MailerliteConnect/AbstractMailerliteConnect. php on line 35 * Notice: Undefined index: emailoctopus_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/EmailOctopusConnect/AbstractEmailOctopusConnect. php on line 33 * Notice: Undefined index: sendinblue_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/SendinblueConnect/AbstractSendinblueConnect. php on line 37 * Notice: Undefined index: getresponse_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/GetResponseConnect/AbstractGetResponseConnect. php on line 33 * Notice: Undefined index: getresponse_is_360 in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/GetResponseConnect/AbstractGetResponseConnect. php on line 34 * Notice: Undefined index: getresponse360_registered_domain in /home/learnc20/public_html/ wp-content/plugins/mailoptin/src/connections/GetResponseConnect/AbstractGetResponseConnect. php on line 35 * Notice: Undefined index: getresponse360_country in /home/learnc20/public_html/ wp-content/plugins/mailoptin/src/connections/GetResponseConnect/AbstractGetResponseConnect. php on line 36 * Notice: Undefined index: klaviyo_api_key in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/KlaviyoConnect/AbstractKlaviyoConnect.php on line 33 * Notice: Undefined index: convertfox_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/ConvertFoxConnect/AbstractConvertFoxConnect. php on line 33 * Notice: Undefined index: mailchimp_api_key in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/MailChimpConnect/AbstractMailChimpConnect.php on line 37 * Notice: Undefined index: drip_api_token in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/DripConnect/AbstractDripConnect.php on line 35 * Notice: Undefined index: drip_account_id in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/DripConnect/AbstractDripConnect.php on line 36 * Notice: Undefined index: sendlane_api_key in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/SendlaneConnect/AbstractSendlaneConnect.php on line 35 * Notice: Undefined index: sendlane_hash_key in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/SendlaneConnect/AbstractSendlaneConnect.php on line 36 * Notice: Undefined index: sendlane_domain in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/SendlaneConnect/AbstractSendlaneConnect.php on line 37 * Notice: Undefined index: convertkit_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/ConvertKitConnect/AbstractConvertKitConnect. php on line 33 * Notice: Undefined index: activecampaign_api_url in /home/learnc20/public_html/ wp-content/plugins/mailoptin/src/connections/ActiveCampaignConnect/AbstractActiveCampaignConnect. php on line 33 * Notice: Undefined index: activecampaign_api_key in /home/learnc20/public_html/ wp-content/plugins/mailoptin/src/connections/ActiveCampaignConnect/AbstractActiveCampaignConnect. php on line 34 * Notice: Undefined index: mailerlite_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/MailerliteConnect/AbstractMailerliteConnect. php on line 35 * Notice: Undefined index: emailoctopus_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/EmailOctopusConnect/AbstractEmailOctopusConnect. php on line 33 * Notice: Undefined index: sendinblue_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/SendinblueConnect/AbstractSendinblueConnect. php on line 37 * Notice: Undefined index: getresponse_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/GetResponseConnect/AbstractGetResponseConnect. php on line 33 * Notice: Undefined index: getresponse_is_360 in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/GetResponseConnect/AbstractGetResponseConnect. php on line 34 * Notice: Undefined index: getresponse360_registered_domain in /home/learnc20/public_html/ wp-content/plugins/mailoptin/src/connections/GetResponseConnect/AbstractGetResponseConnect. php on line 35 * Notice: Undefined index: getresponse360_country in /home/learnc20/public_html/ wp-content/plugins/mailoptin/src/connections/GetResponseConnect/AbstractGetResponseConnect. php on line 36 * Notice: Undefined index: klaviyo_api_key in /home/learnc20/public_html/wp-content/ plugins/mailoptin/src/connections/KlaviyoConnect/AbstractKlaviyoConnect.php on line 33 * Notice: Undefined index: convertfox_api_key in /home/learnc20/public_html/wp- content/plugins/mailoptin/src/connections/ConvertFoxConnect/AbstractConvertFoxConnect. php on line 33 Viewing 1 replies (of 1 total) * Plugin Author [Collins Agbonghama](https://wordpress.org/support/users/collizo4sky/) * (@collizo4sky) * [7 years ago](https://wordpress.org/support/topic/errors-using-mailoptin/#post-11557007) * While we are going to ensure the PHP errors are fixed. You shouldn’t have WP_Debug set to true on a production or live site. * Set it to false and you won’t see those PHP errors Viewing 1 replies (of 1 total) The topic ‘Errors using MailOptin’ is closed to new replies. * ![](https://ps.w.org/mailoptin/assets/icon-256x256.png?rev=1699978) * [MailOptin - Popup, Optin Forms & Email Newsletters for Mailchimp, HubSpot, AWeber Etc.](https://wordpress.org/plugins/mailoptin/) * [Frequently Asked Questions](https://wordpress.org/plugins/mailoptin/#faq) * [Support Threads](https://wordpress.org/support/plugin/mailoptin/) * [Active Topics](https://wordpress.org/support/plugin/mailoptin/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/mailoptin/unresolved/) * [Reviews](https://wordpress.org/support/plugin/mailoptin/reviews/) * 1 reply * 2 participants * Last reply from: [Collins Agbonghama](https://wordpress.org/support/users/collizo4sky/) * Last activity: [7 years ago](https://wordpress.org/support/topic/errors-using-mailoptin/#post-11557007) * Status: resolved