Link to my form sometimes shows an error page

On my page https://www.legendaryletters.com/*Christmas-Telegram-Santa-gram-p64685308 I have customers check a box that says, "I have submitted the personaliz​ation form https://fo​rm.jotform​.com/61666​374203960". The form is also embedded in listing description. However, customers are letting me know that when they copy and paste the link, they get a "whoops! Page not found" error. I have also duplicated this error. Sometimes the page loads and sometimes it gives the error. It's about 50/50. Can you please look into this? It's for my form titled Holiday Telegrams Form. When I click on publish and copy the link I get the exact same one, but the one on my page gives the error. If I copy directly from publish and paste into my browser, it will load.

https://form.jotform.com/61666374203960

When I copy and paste from my site, it inserts % signs into the URL.

Please remove that URL, and copy your form URL as shown on this guide: https://www.jotform.com/help/401-Where-to-Find-My-Form-URL 

That's exactly how I pasted it into the web page (using the guide you mention). It's still doing the thing where it adds percent signs if you copy it and paste it into a browser. So then my customers get the whoops page.

Probably those characters are added by your site. Try hyperlinking the URL:

<a href="LINK OF YOUR FORM COPIED FROM QUICK SHARE" target="_blank">https://form.jotform.com/61666374203960</a>