Some issues with MS Flow and NAV

Hi, community,

Some time ago I wrote a blog about “How to connect MS Flow and NAV”. Many people used it in their projects. 

Recently I received a message from one of my subscribers Murat Vezir, who noticed that MS Flow doesn’t work on big tables. For example, if you want to send a notification when a sales order is deleted, it works when you have 10 sales orders and don’t work when you have 1000. 

You simply get this Error “Bad Request – Request Too Long”.

You can see this error here :

1. Login to 

2. Go to Notifications. You will see something like this


3. Click on it. And you will see failure description

 Bad Request - Request Too Long
 HTTP Error 400. The size of the request headers is too long.

So what is the maximum size?

First, I thought on “Max Page Size” property in Odata Tab of Dynamics Nav Server setup, which is 1000 by default. But playing with that I got the same result for 500 and even 250 sales orders…

That was really strange. 

Also while experimenting I’ve got another error

"status": 400, "message": "Invalid Mashup Expression using supplied values.\r
inner exception: The value does not support deltas."

This one I’ve got just after the bulk creation of 1000 Sales orders.

The solution was pretty simple, but I will say this is bug… not feature.

You need to create a copy of flow and delete the old one. After recreation, it starts to work…


but after a while, it falls in error once again… =(

What I’ve got at the end of playing with this? If the number of sales orders, not more than 200 than MS Flow works without errors. If the number is greater that you will have error 

HTTP Error 400. The size of the request headers is too long.

I saw many issues about this on Flow forum and also reported about this issue there

Also, there are some Flow limitations.

But before they fix this be careful on using it with big tables.

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A Microsoft MVP, Business Central architect and a project manager, blogger and a speaker, husband and a twice a father. With more than 15 years in business, I went from developer to company owner. Having a great team, still love to put my hands on code and create AI powered Business Central Apps that just works.

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