The error message is generated when the browser cannot resolve a URL. In Conga, this is generally caused by a malformed URL in your Composer button.
Typical causes can include:
- Spaces within the URL
- Spaces at the end of the URL
- Missing an ampersand (&) between parameters
- Using a URL pointing to an invalid server (such as beta vs. www)
What to Do
Remove all spaces from the button's URL. Use plus signs instead of spaces in a parameter. Plus signs render as spaces in the Composer merge operation, but do not lead to 404 authorization errors.