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How to Update Project Online Task Custom Fields via Power Automate REST API
Question details
The user needs to update custom task or schedule fields in Project Online using a Power Automate flow.
- Product
- Project Online and Power Automate
- Device & OS
- not provided
- Scenario
- Configuring the 'Send an HTTP Request to SharePoint' action with the correct REST API endpoint and JSON payload to modify custom task fields.
- Observed behavior
- The user is seeking the precise URI structure and JSON request body format required to successfully execute the API call without endpoint or permission errors.
Ensure that the account running the Power Automate flow has administrative or edit permissions in your Project Web App (PWA) environment, and verify the exact internal names of your custom fields.
Consult the Power Automate Community for API Specifications
Because custom field internal names and JSON payloads vary heavily based on your specific Project Online environment, requesting the exact structure from the Microsoft Power Automate Community is the most reliable approach.
The Project Web App (PWA) REST API requires specific GUIDs for both the project and the task, as well as exact internal field names. If your JSON request body is improperly structured, the HTTP request will fail.
Navigate to the Microsoft Power Automate Community forums at powerusers.microsoft.com.
Create a new thread detailing your Project Online setup, the specific custom task fields you want to update, and screenshots of your current flow configuration.
Once the support engineers provide the exact `_api/ProjectServer/Projects('id')` endpoint and JSON schema, copy them into your HTTP action.
Configure the Send an HTTP Request to SharePoint Action
Set up the foundational framework for your REST API call in Power Automate before applying the specific JSON payload.
Simplify Your Task Tracking with WPS Office
While Project Online and Power Automate handle complex enterprise APIs, managing everyday project trackers shouldn't be complicated. WPS Office provides a completely free, highly compatible alternative for managing tasks and schedules using powerful spreadsheets without the need for complex API configurations.
- 1. Download WPS Office: Visit the official WPS website to download and install the free office suite.
- 2. Open your project files: Launch WPS Spreadsheets to easily open and edit your existing Excel project trackers.
- 3. Track tasks efficiently: Utilize built-in formulas, data validation, and templates to keep your project tasks organized.
Frequently Asked Questions
What is the correct HTTP method to update Project Online fields via REST API?
To update existing fields, you typically use a PATCH or MERGE request directed to the `_api/ProjectServer` endpoint, targeting the specific project's Draft and Task GUIDs.
Why am I getting an 'Access Denied' error in my Power Automate HTTP request?
This error usually occurs if the account running the Power Automate flow lacks the necessary edit permissions in the Project Web App (PWA), or if the SharePoint Site Address in the HTTP action is pointing to the wrong site collection.
Can I update Project Online custom fields using standard SharePoint list actions?
No. Enterprise custom fields in Project Online require specific ProjectServer REST API calls. Standard SharePoint list update actions in Power Automate will not work for PWA project tasks.
How do I find the internal name of a Project Online custom field?
You can query the `_api/ProjectServer/CustomFields` endpoint directly in your web browser. This will return an XML or JSON feed containing the exact internal names and GUIDs needed for your API payload.
