How to prepare for AB-400 before official courses exist

With no official courses, the only document that defines the exam is the AB-400 study guide on Microsoft Learn. It has close to ninety objectives across four domains. Go through all of them and sort each into three groups: I do this at work, I have read about it but never done it, I do not know what it is. The third group is your study plan; the second is your practice list.

Look at the change log at the end of the guide too: area by area, it says whether the change from PL-400 is minor, major or new. It is the fastest way to see where the older material is still enough. We summarize it in the AB-400 skills outline by domain.

The areas marked as minor or no change are the familiar ones: Dataverse plug-ins and the execution pipeline, PCF components, client scripting, Azure Functions, Dataverse events, data synchronization and custom connectors. The Microsoft Learn modules attached to PL-400, still published as of today, apply to all of them, along with the Dataverse and model-driven apps developer documentation.

It is also the part you can measure with questions. The CertifyDeck AB-400 bank follows the domains of the new outline with an explanation on every answer: use it to find gaps in plug-ins, Web API, PCF, connectors and integrations before spending time on the new material. It also includes questions on the new areas, written from the official documentation and due for review once Microsoft publishes its training. The AB-400 study guide also still links to the free PL-400 practice assessment, which is useful to diagnose the core.

Power Apps code apps take two of the four areas in the user experience domain (25–30%). The effective way to study them is to build one: create a code app with your usual web framework, connect it to a Dataverse table and a connector, call a Power Automate flow and a Copilot Studio agent from it, and use environment variables for configuration.

Then walk the deployment objectives with that same app: configure the Content Security Policy, add Application Insights, package and share it, and troubleshoot it with Monitor and browser tools. By the end you will have touched every objective in both areas, which is exactly what the exam asks: not theory, but what gets configured where.

The AI material is spread across the outline. In design (domain 1) you are asked when to use deterministic or non-deterministic logic and when to choose Foundry or Copilot Studio. Domain 3 holds the area on Microsoft Foundry agents built with code: integrating them through Power Platform MCP servers, connecting them to Copilot Studio agents, giving them Dataverse data through Work IQ and consuming Copilot Studio agents with the client library. Copilot Studio workflows also appear alongside Power Automate.

Study the concepts first (what an MCP server is, how a Foundry agent differs from a Copilot Studio one, what Work IQ adds) in each product's documentation, then do one minimal exercise: a Foundry agent that uses the Dataverse MCP server to query a table. If you have never worked with Copilot Studio, the AB-620 outline covers that tool in depth and its practice questions give you the foundation; AB-400 needs less depth, but you do need to understand topics, tools and how an agent connects to the rest of a solution.

A simple rule: time in proportion to weight, adjusted for what you already know. If you were preparing PL-400, your core is well along and most of your hours should go to code apps, platform APIs (limits, retries, bulk operations, the Python SDK) and agents. If you are starting from scratch, a sensible order is Dataverse and plug-ins, then APIs, then user experience and finally agents and integrations.

On timing: a newly released exam usually has less third-party material and more uncertainty about question style. If you are not in a hurry, sitting a few weeks after 16 October gives Microsoft time to publish its learning paths. If you need the certification now and your PL-400 preparation is advanced, remember you can register for PL-400 until 16 October 2026 and sit it through 30 October; we explain it in PL-400 is becoming AB-400.