Hello @WendyMastaler
Thank you for contacting the Instructure Community. We're sorry to hear you've been experiencing issues with creating an assignment in Mastery Connect. The photo you provided is a little difficult to read exactly what the error message is saying. It is likely your internet browser and we recommend clearing the cache and cookies or trying another browser.
In Chrome
On your computer, open Chrome.
At the top right, click the three dots
Click settings
On the left, choose Privacy and Security
Then, clear browsing data
At the top, choose a time range. To delete everything, select All time. I suggest at least 4 weeks
Next to "Cookies and other site data" and "Cached images and files," check the boxes.
Click Clear data.
If that doesn't work, can you replicate this error on a difference browser or device? If it doesn't work, can you provide a clearer picture and/or type out what the message says?