Anyone encountered this before? Failed to retrieve form control for canvas. Object reference not set to an instance of an object. It appears when changing Single Line Textbox's 'Connected to' attribute. Though values are being set as what you have intended, error is a bit bothering during development.

Error occur on a newly setup environment. The old development environment doesn't throw this error. The only difference is, the new one runs on SQL 2014 backend, while the old on 2012.

I've tried re-installing, setting SQL DB roles (WSS_Content_Application_Pools), and probably all other fixes I can see in this forum and outside.

Exact error is:

Failed to retrieve form control for canvas. Error: Object reference not set to an instance of an object.. Stack trace:    at Nintex.Forms.SharePoint.Services.NfWcfService.GetUpdatedFormControlForCanvas(FormControlProperties formControlProperties, FormVariable variable).