I’m building a Power Automate flow that needs to loop over 6 months of calendar events, and find events that contain a string in part of the subject line. Using the ODATA filter makes the flow perform much faster than filtering in a separate action within the flow, but it seems to be case sensitive.

Am I missing something with my configuration? Or is Power Automate’s toUpper function causing a conflict with ODATA’s toupper?

• Error:
  Action ‘Get_Calendar_events’ failed: The query filter contains one or more invalid nodes. clientRequestId: 6e870362-b6f0-44a4-88bb-e82a678e3d48 serviceRequestId: faeebaca-3a65-4d06-bcc9-08b86fa7edd2

– Input parameters:
{
“calendarId”: “–“,
“startDateTimeUtc”: “2024-09-06T15:11:53.4906978Z”,
“endDateTimeUtc”: “2025-04-06T15:11:53.5200459Z”,
“$filter”: “contains(toupper(subject), ”)”,
“$orderby”: “Start/DateTime”
}

I looked for other options for make the subject case insensitive. I’ve tried using an escape characters to prevent Power Automate from using its toUpper function and reviewing ODATA documentation. Also tried tolower.