Issue with password reset while using custom mongoDB

I am facing problem with forget password button, When I click the button forget password, email is generated and upon clicking the link in the email it goes to password reset page no issues but when I change the password and click change password, I get redirected to login page and password is changed at my db and user can login using the new password, but at the redirect URL getting this error message -

success=false&message=The operation cannot be completed. Please try again

Log entry:

"date": "2017-08-28T04:48:20.433Z",
  "type": "fcp",
  "description": "The operation cannot be completed. Please try again.",
  "connection": "***********",

For a custom database connection the reset password flow goes through your own code, in particular, it requires the execution of the custom database scripts you provided so it’s difficult to provide definitive answers without knowing the exact implementation being used.

However, you mention that the password is changed at your custom store so this suggests that the Change Password script associated with the connection is being called. Have in mind that the script needs to change the user password, but also communicate the outcome of that operation, in particular and as stated in the initial script template, the script needs to terminate with callback(null, true); when it wants to signal that the user’s password was updated successfully.

As mentioned initially, without the possibility to fully replicate the system (only you have access to your custom store) it’t not feasible to directly troubleshoot the situation so the best recommendation is for you to review the custom scripts you provided and ensure that they meet the desired contracts (aka communicate the outcome of the operations as expected).