Title: Cannot modify header information
Last modified: April 20, 2023

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# Cannot modify header information

 *  Resolved [umduck](https://wordpress.org/support/users/umduck/)
 * (@umduck)
 * [3 years, 1 month ago](https://wordpress.org/support/topic/cannot-modify-header-information-187/)
 * We are seeing this warning multiple times per day, removed and reinstalled plugin,
   still happening?
    - **Message:** Cannot modify header information – headers already sent
    - **File:** /wp-content/plugins/mailchimp-for-woocommerce/bootstrap.php
    - **Line:** 1443
    - **Request:** /wp-cron.php?doing_wp_cron=1682012432.5584321022033691406250

Viewing 2 replies - 1 through 2 (of 2 total)

 *  Plugin Support [khungate](https://wordpress.org/support/users/khungate/)
 * (@khungate)
 * [3 years, 1 month ago](https://wordpress.org/support/topic/cannot-modify-header-information-187/#post-16689971)
 * Hi [@umduck](https://wordpress.org/support/users/umduck/), thanks for reaching
   out. As a first step for troubleshooting. Let’s try to work through the following:
    - Verify the latest plugin version is being used (v2.8.3 at the time of this
      post)
    - Switch themes to the default WooCommerce one, deactivate all plugins except
      WooCommerce and Mailchimp for WooCommerce, and test the scenario again – ideally
      in a staging enviornment.
    - Test for conflicts by following this guide, WooCommerce: Fixing Theme and 
      Plugin Conflicts: [https://docs.woocommerce.com/document/how-to-test-for-conflicts/](https://docs.woocommerce.com/document/how-to-test-for-conflicts/)
    - Check for possible [caching issues](https://github.com/mailchimp/mc-woocommerce/wiki/Using-Caches)
      caused by the hosting provider.
    - Try uninstalling and reinstalling the plugin from scratch.
 * Let us know if any of those help you resolving this issue.
 * Thanks!
 *  Plugin Support [khungate](https://wordpress.org/support/users/khungate/)
 * (@khungate)
 * [3 years ago](https://wordpress.org/support/topic/cannot-modify-header-information-187/#post-16749397)
 * Hi [@umduck](https://wordpress.org/support/users/umduck/), we’re going to close
   out this ticket for now since it’s been a few weeks since we’ve been in touch.
 * Please let us know if you still need any help and we’ll be glad to reopen and
   troubleshoot further. Please note, that the best way to reach us is over at the
   GitHub plugin page: [https://github.com/mailchimp/mc-woocommerce/](https://github.com/mailchimp/mc-woocommerce/).
   From there, you can receive direct responses from the development team, log new
   issues, download the latest version, and track existing support tickets.

Viewing 2 replies - 1 through 2 (of 2 total)

The topic ‘Cannot modify header information’ is closed to new replies.

 * ![](https://ps.w.org/mailchimp-for-woocommerce/assets/icon-256x256.png?rev=1509501)
 * [Mailchimp for WooCommerce](https://wordpress.org/plugins/mailchimp-for-woocommerce/)
 * [Frequently Asked Questions](https://wordpress.org/plugins/mailchimp-for-woocommerce/#faq)
 * [Support Threads](https://wordpress.org/support/plugin/mailchimp-for-woocommerce/)
 * [Active Topics](https://wordpress.org/support/plugin/mailchimp-for-woocommerce/active/)
 * [Unresolved Topics](https://wordpress.org/support/plugin/mailchimp-for-woocommerce/unresolved/)
 * [Reviews](https://wordpress.org/support/plugin/mailchimp-for-woocommerce/reviews/)

 * 2 replies
 * 2 participants
 * Last reply from: [khungate](https://wordpress.org/support/users/khungate/)
 * Last activity: [3 years ago](https://wordpress.org/support/topic/cannot-modify-header-information-187/#post-16749397)
 * Status: resolved