Power Platform Community Forum Thread Details

Hi,

I have a Copilot Studio topic that uploads:

1 required PDF

1 optional PDF

The topic calls a Power Automate flow using When an agent calls the flow.

The flow works in Copilot Studio Test, but fails when run through the actual agent chat.

In the agent chat, the user gets Connect to continue prompts for:

SharePoint

Word Online

Microsoft Copilot Studio

AI Builder

The flow then fails at the AI Builder OCR step:

OCR_Extract_Text

Error:

The base 64 binary content is missing for input single

I have already checked/tried:

same PDF works in Test

topic file upload works

topic passes file as contentBytes + name

tried OCR input from both trigger content and SharePoint Get file content

tried adding delay before OCR

connection references exist

What makes this confusing is:

it works in Test

it fails only in the published agent chat

the user first gets a Connect to continue / Allow access prompt for some connectors

then, when the flow reaches the AI Builder OCR step, a second Allow access prompt appears specifically for AI Builder

that second prompt appears at the same time the OCR action is already trying to run, so there is no real chance to approve it before the action fail.

Because of that, the current suspicion is that this is not a PDF problem or a pure flow logic problem, but a runtime connection/authentication issue when the agent calls the flow. More specifically, the AI Builder connection does not seem to be fully established before the OCR step executes, which causes OCR to receive missing/null content and fail.

Main questions:

Is this a known issue or limitation with Copilot Studio agent chat + When an agent calls the flow?

How should the connections be configured so users do not get repeated Connect to continue / Allow access prompts during the same run?

Is there a way to ensure the AI Builder connection is authorized before the OCR action starts?

Should this be set up with owner/service connections instead of user runtime consent?

If anyone has seen this before, I would appreciate guidance.

Categories:

Bot administration

Calling actions from Copilot Studio

Topic creation & management

Hi! You've done excellent diagnostics. The issue you're describing is a well-known connection configuration pattern — here's the explanation and fix.

Why it works in Test but fails in the published agent chat

In the Copilot Studio Test pane, flows run under your maker credentials, so all connector connections are pre-authenticated. In the published agent chat, flows run in the context of the end user — and unless connections are configured as "owner" connections, end users are prompted to authenticate each connector at runtime. This is the root cause of the "Connect to continue" prompt appearing mid-flow.

The fix: Configure connections as service/owner connections

Per Use agent flows with your agent – Microsoft Learn, Power Automate flows called from Copilot Studio agents support connection references that can be set to use the flow owner's connection rather than requiring end-user authentication.

Steps

In Power Automate, open the flow in Edit mode.
Check the connections used (SharePoint, Word Online, AI Builder, Copilot Studio).
Ensure each connection is authenticated with a service/maker account that has the necessary permissions.
In the flow's Settings, verify there is no "run-only" user connection that would prompt the end user at runtime.
For AI Builder specifically: make sure the AI Builder connection is fully authenticated before publishing.

Additional check

Consider migrating the flow to an Agent Flow using the "When an agent calls the flow" trigger — these are optimised to avoid user-facing connection prompts. Per Microsoft Learn, agent flows provide a seamless maker experience and avoid runtime auth prompts.

References

Use agent flows with your agent – Microsoft Learn

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Raghav Mishra — LinkedIn | PowerAI Labs