1. Navigate to Communities > Special Events > Friends Asking Friends > Kintera Thon.
  2. Hover over your event and select Website Info.
  3. Next to Friendly URL, click Release. 
  4. Click Publish This Event Now.
  5. Next to Friendly URL, click Edit.
  6. Add your Friendly URL again.
  7. Return Webinfo Checklist and click Publish This Event Now.
  8. Check your friendly URL to see if this resolves the problem

If this does not resolve the problem, Chat with Support and reference this article.