We find out that certain kinds of search folder with cause the mail folder delta API broken. The problematic folder kind is the 'follow-up' ones, such as 'Flagged for follow-up'. Usually such kind of folders will not appear under the normal mail root. However, if you delete them from the 'Search Folder', then they will go to the 'Deleted Items', which is under the normal mail root, and therefore the mail folder delta API will try to include them. This will make the delta API responds with 'ErrorUnsupportedPropertyDefinition' error. Here are the specific steps to reproduce this issue: 1. From the Outlook Online (owa) page, right click to the 'Search Folder'. 2. Select the 'Flagged for follow-up' kind, and give it any name. (ex: ABC) 3. Right click to the newly created folder (ex: ABC), and delete, then they will go to 'Deleted Items'. 4. Send the Graph API mail folder delta [1], and it will respond with the following message: {
"error": {
"code": "ErrorUnsupportedPropertyDefinition",
"message": "PropertyDefinition is not supported in searches."
}
} Besides, according to our test, if you prevent from listing the 'SizeInBytes' field, then you can get the success API response instead. For example, appending the following $select to the query will do: $select=id,displayName,parentFolderId,childFolderCount Therefore, we also doubt that if the 'Flagged for follow-up' kinds are missing 'SizeInBytes' field, which leads to the delta API abnormality. Do anyone also encounter this issue? It would be great if Microsoft developers could get it right. [Edit at 2023/09/17 23:42] Update the reference link to the mail folder delta API page: [1] mailFolder: delta - https://learn.microsoft.com/en-us/graph/api/mailfolder-delta?view=graph-rest-1.0&tabs=http Thank you.
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