Maximum number of headers in one message should be less than or equal to 5 (error message)

[LearnDayByDay]

Hi, i am now getting this error message "Maximum number of headers in one message should be less than or equal to 5." for a flow that has been running without any issues, but it began 3 days ago. No changes were made to the flow and i cannot find on here or the net for a solution. Please help

[LearnDayByDay]

"body": {
"status": 400,
"message": "Maximum number of headers in one message should be less than or equal to 5.\r\nclientRequestId: 42a6c729-9a79-43c3-8e8b-1a2bb6c24adf\r\nserviceRequestId: 3aadf9ce-0857-2f25-cf8f-9cd2d6bb0164",
"error": {
"message": "Maximum number of headers in one message should be less than or equal to 5.",
"code": "InvalidInternetMessageHeaderCollection",
"originalMessage": "Maximum number of headers in one message should be less than or equal to 5."
},
"source": "office365-wus2.azconn-wus2-001.p.azurewebsites.net"
}

[fun]

 I am also experiencing the same issue. The flow stopped working on Oct 21st. Please, could you advise on how to resolve this? The input to the flow seems correct.

[LearnDayByDay]

I have a ticket open with internal IT. Will keep you updated on here if and when it gets sorted.

[iSQL]

+1; same issue.  Flow has been working without issue for months.  No changes to the flow.

First failed on 10/22.  Last successful email sent through Flow on 10/20. Since we have conditional logic based on date and no email would have been sent based on the logic for 10/21, can't be sure if issue first started on 22nd or if it would have occurred on 21st all the same.

Any suggestions would be appreciated.

[jreypo]

Any finding around this error? I've got the same error yesterday and today in one of my flows.

[LearnDayByDay · Accepted solution]

i am in contact with IT and have an Incident Ticket open, they have suggested this: "Could you please remove and re-add the connector which is giving the error Action ' Send an email ' and also please try to create a new flow and let us know if it still gives the same error"

Busy trying this before i go back to them with my results..perhaps try it as well?

[ArtL]

I have tried. This did not work for me and I am getting the same error. It seems to be dependent upon the number of people I send it to. It works if I just send the mail to myself. 😞 

[ArtL]

It appears to be directly related to the number of headers and / or sensitivity options you set. (Ergo, more stuff in the headers.) 

[FfionLim]

This is seriously frustrating. This is happening to me too. I couldn't find any workaround for this

[FfionLim]

Instead of sending an email, i amended my flow to "create an event" with the same html codes. It manage to send out. This could be a potential workaround for anyone affected. I just set the status to "Free" and all day value to "true". Receiver's calendar will not be "blocked" and they will be able to read the content in their inbox. 

[LearnDayByDay]

Turn off your flow. Recreate it again on a new Flow, that's what i did and it works again.

[Melinda]

I was having the exact same issue. I tried the solution provided of re-adding the send email however that didn't work either. What did work was removing the sensitivity label designation from the advanced settings on the Send Email trigger. 

[FfionLim]

Thanks Melinda, this solution works for me! 

[FfionLim]

Your solution works as well but I have over 40 flows affected. Creating them 1 by 1 from scratch really isn't an ideal solution for me 😞 But amending the sensitivity level of the outlook connector did resolve my issue! Maybe you can give it a go too. It does save us a tone of time to recreate brand new flows 😄

[Melinda]

I'm happy to hear that worked! Hopefully they'll fix this issue or provide a better workaround because I would really like to continue using the sensitivity label. 

[HeadScratching]

Is there any other ways to solve the issue? I can't change the sensitivity of the email due to the nature of the work. Tried creating new flow etc as well but to no avail

[Melinda]

If you can't remove the sensitivity, you could try to remove another header? Reply-to, Importance etc? Not sure if that would work but it might be worth trying. 

[fun]

I think the header issue is resolved now. My old flow started working again today.