Microsoft project management software used to plan, manage, and communicate a project schedule and other information among workgroup members, project managers, and other stakeholders.
Dear LaurenFS,
Good day! Thank you for posting to Microsoft Community. We are happy to help you.
As per your description, first, please accept my apologize (it’s my humbly request please don't mind) because you meet such a problem.
In this community I check there is similar error message in a Microsoft Project Web APP. I also checking from our side, we didn't find any Service Incident (SIE) related to this Project issue.
Since problem happened to Microsoft Project Web APP and if all uses in your organization. The possible reason of this problem is related to the server side and I'm afraid needs to be check/ investigated from back-end side to find the root cause.
In this situation, we sincerely recommend you contact your Microsoft 365 administrator, follow steps in this article and create a support ticket. The support team over there has higher permission than us, they can remotely help you and collect logs when try to access Microsoft project web app. They can also involve more resource to investigate the issue from back end. This would be the most efficient way in handling this case for you.
For reference: How do I find my Microsoft 365 admin?
Your understanding and patience will be highly appreciated. I hope that you are keeping safe and well!
Sincerely,
Waqas Muhammad