I tried to do it with list lookup, but the problem was that the values added by jquery was lost when I submitted the form, any ideas??

Omar Taha‌
Remove the white spaces for all the drop down lists within Nintex form. I had exactly same issue and found that Drop down fields has white spaces. I removed all drop down lists within Nintex form and it worked. 

Try if it works ..

In my case, I was manipulating list lookup controller options using javascript, and that was making my problem. I figured this after one week of searching for my problem  

Thanks ‌ for your reply.

Hello,

i have the same issue, did you find a solution?

Thanks

Amine Charraqua‌ 

At times there could a couple a white spaces in Drop Down spaces in your unbound fields within the form.
Remove the white spaces for all the drop down lists within Nintex form and it should work. 

Could you please elaborate your suggestion, removing white spaces in where? 

Hi All, 

I found the same issue.. I am dynamically preparing the dropdown values and while appending the final text to the dropdown there was a space. After removing the space i did not observe any error.

I second ‌'s comment: what white space are you talking about? From the option text? That would make my options hard for the user to read. Please elaborate.

Was this ever solved?

I'm having the exact same issue, but I'm not sure what it's meant by 'remove the white space'.

Where do I remove the space?

I am facing the same issue, is anyone here to resolve this issue?

I was able to work through my issue, although it's not ideal. I plan to post my solution in detail, but I did give a basic explanation of how I accomplished it on this post.

I am using drop-down filled by lookup values, still not working as that drop down is unbound field. Also I removed white spaces through JS. But still not working

Has anyone found a solution to this issue? I am using a dropdown choice field. I am appending values to the existing choices through jquery. But when I am selecting anything from additional choices added through jquery, my form throws an error. It works fine with values added through the list.

This is the error I am getting:

Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.

Have you found a solution yet?

Is there any way you can add all possible options through the list and then remove what you don't need?