Title: Error – Header not valid? Last modified: August 6, 2017 --- # Error – Header not valid? * Resolved [c4aig](https://wordpress.org/support/users/c4aig/) * (@c4aig) * [8 years, 9 months ago](https://wordpress.org/support/topic/error-header-not-valid/) * Getting an error upon activation stating the plugin does not have a valid header. Viewing 2 replies - 1 through 2 (of 2 total) * Plugin Author [mondula2016](https://wordpress.org/support/users/mondula2016/) * (@mondula2016) * [8 years, 9 months ago](https://wordpress.org/support/topic/error-header-not-valid/#post-9387549) * Hi, please step back to a standard WP-Theme and try again. If this works fine you can find out the misconfiguration by checking the different PlugIns and themes… Hope this might help. Not every PlugIn and Theme configuration can be tested by us. Otherwise please contact us again. best. * Mondula team * [hunts57](https://wordpress.org/support/users/hunts57/) * (@hunts57) * [8 years, 8 months ago](https://wordpress.org/support/topic/error-header-not-valid/#post-9490498) * I had the same issue. It was conflicting with another form plug-in. Viewing 2 replies - 1 through 2 (of 2 total) The topic ‘Error – Header not valid?’ is closed to new replies. * ![](https://ps.w.org/multi-step-form/assets/icon-256x256.png?rev=1553626) * [Multi Step Form](https://wordpress.org/plugins/multi-step-form/) * [Frequently Asked Questions](https://wordpress.org/plugins/multi-step-form/#faq) * [Support Threads](https://wordpress.org/support/plugin/multi-step-form/) * [Active Topics](https://wordpress.org/support/plugin/multi-step-form/active/) * [Unresolved Topics](https://wordpress.org/support/plugin/multi-step-form/unresolved/) * [Reviews](https://wordpress.org/support/plugin/multi-step-form/reviews/) * 2 replies * 3 participants * Last reply from: [hunts57](https://wordpress.org/support/users/hunts57/) * Last activity: [8 years, 8 months ago](https://wordpress.org/support/topic/error-header-not-valid/#post-9490498) * Status: resolved