SYMPTOM:
When opening a project in Strategy Object Manager 9.4.1, users may see the following error:

This occurs even after the Use Object Manager Read-only privilege is disabled for all users and groups and the two checkboxes in the Tools > Object Manager Preferences > Object Manager > Connection window are unchecked as seen in the following screenshots, respectively:

CAUSE:
The error could still be occuring due to a lingering privilege on the particular user in question or on a group that the user is in.
ACTION:
Try using a Find and Replace Privileges to force-remove the Use Object Manager Read-only privilege from all users and groups. See the following steps to do so:
1) Log into the project source in question and browse to the user editor. Right-click in the right pane and select Find and Replace Privileges as seen in the following screenshot:

2) In the window that pops up, select to Examine all Users, User Groups, and Security Roles that match All for Use Object Manager Read-only and apply the Revoke option for Use Object Manager Read-only as seen in the following screenshot:

After clicking the Go button in the bottom-right, this privilege will be revoked from all Users, User Groups, and Security Roles, and all users should be able to once again log into projects in Object Manager without receiving the error.