Hi Rhyannon,
I was able to reproduce the error message in my own test environment. The recommendations in this document helped me resolve it:
https://docs.skuid.com/latest/v1/en/skuid/deploy/salesforce/visualforce/#troubleshooting
Specifically: These errors may be related to the action attribute in your Visualforce markup, especially if you’re working with actions other than tab and list.
Try replacing {!redirect}?page= with {!redirect}&page= or vice versa.
These issues relate to URL parameters and their temperamental punctuation. The ? and & characters are used to indicate variables that may be of use within a page.
The ? character must always be used for the first variable in a URL. Using the & character for a URL’s first variable will cause errors. You also cannot use ? after there is already another ? in the URL. This is why, depending on the Salesforce action you are overriding, you may need to swap a ? for an & or vice versa.