Chronoforms V5 404s on save

I have a particularly large form that will not save in Chronoforms v5. Even if I make no changes, and simply click "Save", the page loads for a few seconds, and then I get a 404 error at https://mywebsite.com/administrator/index.php?option=com_chronoforms5&act=save&save_act=apply
​
Smaller forms save just fine. New forms also save fine.
​
I didn't notice this issue till after we migrated this particular site to a different hosting provider. I have a feeling there's a PHP setting at play, but I haven't found any errors in the log to help me catch what's happening.
​
Any ideas where I should look?

Hi numinous,
​
The max_post_vars setting, and also check if you have suhosin or any other security module installed on the server which may block requests with large number of variables.
​
Do you have the latest v5 update installed ?
​
Best regards

Following up on this, I'm getting some errors back. Here's what I'm seeing in the error_log:
​
[02-Apr-2018 21:17:29 UTC] PHP Warning: Illegal string offset 'multi_page_5' in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1[02-Apr-2018 21:17:29 UTC] PHP Warning: Cannot assign an empty string to a string offset in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1[02-Apr-2018 21:17:29 UTC] PHP Warning: Illegal string offset 'html_65' in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1[02-Apr-2018 21:17:29 UTC] PHP Warning: Cannot assign an empty string to a string offset in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1[02-Apr-2018 21:17:29 UTC] PHP Warning: Illegal string offset 'data_to_session_64' in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1[02-Apr-2018 21:17:29 UTC] PHP Warning: Cannot assign an empty string to a string offset in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1[02-Apr-2018 21:17:29 UTC] PHP Warning: Illegal string offset 'multi_page_50' in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1[02-Apr-2018 21:17:29 UTC] PHP Warning: Cannot assign an empty string to a string offset in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1[02-Apr-2018 21:17:29 UTC] PHP Warning: Illegal string offset 'file_upload_74' in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1[02-Apr-2018 21:17:29 UTC] PHP Warning: Cannot assign an empty string to a string offset in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1[02-Apr-2018 21:17:29 UTC] PHP Warning: Illegal string offset 'file_upload_74' in /home/ourwebsite/public_html/libraries/cegcore/libs/arr.php(60) : eval()'d code on line 1

Hi numinous,
​
Repeating Max's question : Do you have the latest v5 update installed ?
​
These are all PHP Warnings which happen when a string is treated as an array - PHP used to allow this but later releases do not. As far as I can see the current CFv5 code should be checking for this.
​
Bob

I have the same issue, I'm running the latest version 5, have checked my php and I have tried increasing these values:
​
memory_limit:  256M
max_execution_time: 30  
max_input_time: 60
max_input_nesting_level: 64
max_input_vars: 4500
But to no avail. Any ideas I can check on the server? It is hosted with Siteground.
​
Thanks
​
Lee
​
Following this I've turned on error reporting and getting:
[h1]Request Entity Too LargeThe requested resource/administrator/index.phpdoes not allow request data with GET requests, or the amount of data provided in the request exceeds the capacity limit.[/h1]
Additionally, a 413 Request Entity Too Large error was encountered while trying to use an ErrorDocument to handle the request.