Post becomes unpublished upon editing it and no additional date values or image uploads are possible I have a custom content with a large number of multivalue date fields (around 200-300 values). I created a node and added a large number of dates. When subsequently editing the post, the following occurs:


The post is saved as unpublished
Changes to the body field and other text fields such as tags are saved
No additional dates can be saved
Clicking on Preview doesn't show a preview, but saves the post as unpublished
Upon attempting to upload an image file, the Drupal message "[content-type] [post-title] has been updated" (with the specific values in place of the [...] placeholders) appears, but it appears BEFORE clicking Save; upon saving the post, no file is saved
"The content on this page has either been modified by another user, or you have already submitted modifications using this form. As a result, your changes cannot be saved." appears when clicking Save after the file upload
The node can be made Published from the content administration screen (but not from editing it individually)
The Revision tab is missing even though the content type has revisions enabled by default
The Authored on date is reset to the first time the node become unpublished


I would like to have some instructions as to how to debug this situation.

PS: The site is hosted on Hostgator.com.
I was having a similar problem when editing a node with a field that allowed for unlimited field collection values. Each field collection had 8 input fields, and after adding in over 100 field collection items it stopped adding in more and it would unpublish on Save. 

I could publish it from the content administration screen.

I modified max_input_vars in the server php.ini file from max_input_vars=1000 to max_input_vars=2500 and that allowed for the addition of more field collection items and to keep the node published when saved.