Project Online is switched off. Here's how to open the .MPP files you exported
Microsoft's retirement date for Project Online was September 30, 2026. Project Web App and the OData reporting endpoint stop answering, and Microsoft has not committed to a read-only period or an archive mode afterwards — so the export you made is now the copy of record for those schedules.
Which puts a lot of teams in the same position this week: a folder of .MPP files, and often no Microsoft Project licence left to open them with. The licences tended to lapse on roughly the same schedule as the service.
Open the files in the browser
Ingantt reads the .MPP binary directly — not a task-list summary, not a flattened image. Sign in with a Google account, upload the file or pick it from Google Drive, and the project comes back as a full interactive Gantt chart: sub-tasks, dependencies and lag, resource assignments, calendars, constraints, milestones, baselines, percent complete, costs, and the critical path. The MS Project XML files sitting next to your exports open the same way. It runs in Chrome, Safari, Firefox, or Edge on Mac, Windows, Linux, or a Chromebook, with nothing installed locally and no Project licence involved.
It is not a viewer. An exported plan can be re-planned — move a task and the dependent work and the critical path recalculate — and exported back to MS Project XML for a colleague who still runs Microsoft Project. Opening a .MPP file takes about thirty seconds.
If what you have is CSV, not .MPP
Which files you ended up with depends on how the export was run. Opening each project in Project desktop and saving it locally produces .MPP; Microsoft's bulk User Data Export script produces structured data — CSV and JSON — instead. Ingantt imports CSV, so a task list exported that way can be brought in and rebuilt into a schedule. Be aware of what a CSV carries: the rows, not the scheduling model. Dependencies and baselines that were never written into the file cannot be recovered from it. Where you still had the choice, .MPP or MS Project XML preserved considerably more.
What is not coming back
Anything that was never exported. That is the part worth saying plainly rather than softening: with PWA and OData switched off, an un-exported project should be treated as gone rather than merely offline.
And a folder of .MPP files is a complete backup of your plans, not of your PMO. Timesheet and actual-work history, the enterprise resource pool, enterprise custom fields and lookup tables, portfolio and cross-project reporting, and the issues, risks and documents that lived in each project's SharePoint site were all stored outside the project file. They only ever came out through the OData API or the data export script.
Ingantt does not replace that layer either. Project Online was an enterprise PPM platform — portfolio analysis, proposal and stage-gate workflows, enterprise resource pools, timesheets, OData reporting — and Ingantt does none of it. What it replaces is the scheduling half: the plans, the engine, and the tracking fields. If the portfolio and governance layer is what you actually need, Project Server Subscription Edition or a dedicated PPM product is the honest answer, and the Project Online alternative page sets out what each of Microsoft's recommended destinations costs and drops.
If the problem in front of you is simply that several hundred schedules have to keep working now that the service is gone, start with the files. There is a walkthrough in how to open your Project Online .MPP exports.