Why saveAsync return ImmutableId in Outlook in Exchange online?

[ttuyen1529]

I faced an issue with a tenant of customer cause my app to break since saveAsync return ImmutableId, not normal one then other call using that Id return Id malformed error..
So how it happen for Outlook..
I check in OWA and it did have prefer ImmutableId header in request to Outlook API..

[whoanuragverma]

Hi @ttuyen1529, please let us know about the following details:

1. What platform are you experiencing this issue on? (OWA/Monarch/Old Outlook/Mac)
2. Please provide the code snippet, error message and repro steps.

[ttuyen1529]

Hi @whoanuragverma
This issue I see on a customer online session, I only have time to see it occurs on OWA.
And only with simple code snippet is:

Office.context.mailbox.item.saveAsync((res) => {
if (res.status.toString().toLowerCase() === "succeeded") {
ewsId = res.value;
// convert the item ID to a REST ID
id = Office.context.mailbox.convertToRestId(res.value, Office.MailboxEnums.RestVersion.v2_0);
resolve(id);
console.log(id);
} else {
resolve();
reject();
}
});

After that I use for call additional API to our back-end that use some EWS connection, but it return ID malformed error

I use some console code to check and I see request on customer machine request have this header.. so wonder why it happens on Outlook and where to turn on or off this on Outlook since I never heard Outlook have kind of this setting