Getting "Failed to deserialize input arguments json" when calling flow with string argument

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Posted on by Brad Darragh

I have a simple flow that takes an Text input argument called "Parameter1"

When the parameter value contains no spaces, it works fine.

"C:\Program Files (x86)\Power Automate Desktop\PAD.Console.Host.exe" "ms-powerautomate:/console/flow/run?environmentid=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx&workflowName=\"Test Flow that takes 1 parameter\"&inputArguments={\"Parameter1\":'Bradwashere'}"

When the parameter contains a space, it returns an error.

"C:\Program Files (x86)\Power Automate Desktop\PAD.Console.Host.exe" "ms-powerautomate:/console/flow/run?environmentid=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx&workflowName=\"Test Flow that takes 1 parameter\"&inputArguments={\"Parameter1\":'Brad washere'}"

I am running Power Automate Desktop version 2.55.158.25087

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Michael E. Gernaey 53,963 Moderator on at

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Hi @BD-12020342-0

Can you please type the error in, unfortunately your image probably will never get shown (its a platform thing not your issue"

Also, you have to take into account that you should encode the Uri since it has a space, and then it needs to be decoded after. Since this is essentially a URI

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stampcoin 5,158 Super User 2026 Season 1 on at

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@BD-12020342-0 Hi,

That doesn't look correct, the value of the parameter should be with double-quoted, not single.

inputArguments={\"Parameter1\":'Brad washere'}❌

inputArguments={\"Parameter1\":"Brad washere"}✅

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Brad Darragh 10 on at

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I agree that the JSON Key/Value pair should use double quotes.

The Microsoft documentation indicated that double quotes should use the escape character \"

However, both of these fail.

"C:\Program Files (x86)\Power Automate Desktop\PAD.Console.Host.exe" "ms-powerautomate:/console/flow/run?environmentid=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx&workflowName=\"Test Flow that takes 1 parameter\"&inputArguments={\"Parameter1\":\"Bradwashere\"}"

"C:\Program Files (x86)\Power Automate Desktop\PAD.Console.Host.exe" "ms-powerautomate:/console/flow/run?environmentid=xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx&workflowName=\"Test Flow that takes 1 parameter\"&inputArguments={\"Parameter1\":\"Brad washere\"}"

This is the error message

Exception message: Failed to deserialize input arguments json

I do know that this did work in previous versions of Power Automate Desktop but no longer works in 2.55.

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stampcoin 5,158 Super User 2026 Season 1 on at

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@Brad Darragh Hi,

Could you please reshare your screenshot ? The one you uploaded is not available.

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Brad Darragh 10 on at

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Here is the screenshot of the error that I am seeing.

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Brad Darragh 10 on at

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I really think that this is a defect in the current release of Power Automate Desktop.

How do I formally log this defect with Microsoft?

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Brad Darragh 10 on at

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Hello everyone.

After speaking with Microsoft, I solved the issue.

There are actually two instances of PAD.Console.Host.exe

1. "C:\Program Files (x86)\Power Automate Desktop\PAD.Console.Host.exe"
2. "C:\Program Files (x86)\Power Automate Desktop\dotnet\PAD.Console.Host.exe"

I was using the first path and I was getting the error.

When I use the second path (in the dotnet subdirectory) it works successfully.

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stampcoin 5,158 Super User 2026 Season 1 on at

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@Brad Darragh Hi,

Thanks for sharing.👍

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