This is problem is rare.
- Some computer cannot support special characters. You may see this issue.
- Some Mac machine cannot support some image formats (ie: .png). You may such issue.
Here are my suggestions:
1. Add a new check
- Please add a payee with a simple name. (no special characters in the name, memo or other fields).
- Please make sure you select "Category" field.
Can you save your check this time?
2. If you see error in step 1, click the top menu "Accounts" to add a new account. Please use a simple name for the account. ie: "test". Then add a new check.
Can you save your check in step 2?
3. If you still see this error in step 2, please let us know more about your PC.
- Windows 10, 8.1, 8, 7 or Mac or others?