The Logic Apps SFTP Trigger Mystery No One Warned Me About

Today we encountered an unexpected issue in PROD: the SFTP trigger stopped firing when new files were added to the folder. It had been working fine earlier in the day and then suddenly stopped without any obvious reason.

I was puzzled — there were no recent changes, and the recurrence frequency was already minimal, so nothing pointed to a clear cause.

After some digging, a Microsoft blog provided the clue we needed. When we checked the SFTP folder, we noticed that older, already‑processed files were still sitting there. Once we cleared those files, the trigger immediately started working again.

Even though the folder didn’t contain anywhere near 500 files, it became clear that the SFTP server likely has internal limits or configuration constraints that affect how triggers behave when files accumulate.

Lesson learned: Always clear processed files promptly. As the Microsoft documentation suggests, it’s best practice to keep your monitoring folder and storage folder separate to avoid these issues.

Reference link :https://learn.microsoft.com/en-us/azure/logic-apps/connectors/built-in/reference/sftp/

Original Post https://anithasantosh.wordpress.com/2026/05/19/sftp-when-a-file-is-added-or-updated-doesnt-trigger/