Error message on our registration form

Clients using our registration form have advised us that they are receiving the following error message.  The form still comes through to our email address and populates our Excel spreadsheet that is integrated with the form.  However, the client is unaware of this and has been contacting us to ensure we received the form or they submit it a number of times.  The image below contains the error that people have been receiving.  Please advise as to how we should proceed.

Thanks

Please use this guide to post a screenshot here in the Support Forum: https://www.jotform.com/help/438-How-to-Post-Screenshots-to-Our-Support-Forum

Unfortunately, we cannot see the screenshot or image you provided. Please share it again so we can investigate it further.

We'll wait for your reply. Thank you.

Sorry about that.  Please see the message I get below.  This is when people complete our Jotforms and press Submit - this error appears.  I still get the email auto replies and our integrated spreadsheet is updated but clients don't know that when this is what they see.

I did a test submission to your form and I was not able to replicate the issue. Here's a screen capture of my test submission:

Upon checking it further, I noticed that the form is embedded on a website. Could you please provide the website link so we try to replicate it and investigate further?

Thank you.

?? The form in your answer is for receipts and these are issued by us.  I don't even think the form is active.  The form we have been having an issue with is the Player Registration form.  The website is http://www.3on3superleague.ca/site/3333/page.asp?LeagueID=9806&SeasonID=23&Page=news_league

Our Jotform links are on the left under Registration & Payment.  Please make sure to use 'Test' when filling these out so I know it is not a player registering.

thanks

The forms on under the Registration and Payment in your website are working properly. Here's a screen capture of my test:

I noticed that the forms are not embedded on the website. If you want to embed the form, please follow this guide: https://www.jotform.com/help/34-Adding-a-Form-to-a-Web-Page

Also, please try using a different internet connection just to test it. 

Let us know how it goes. Thank you.

I think I have it figured out.  We had a redirect after submission that would go to another link and then after 5 seconds it would return them to the webpage.  The page that was listed on the redirect is gone so I will have to contact our web provider to see what happened to it.  In the meantime, I have created a new thank you page and changed the redirect and it seems to be working.

Thanks for your work on this.  I really appreciate it.