# Agents now see why a session schedule cron was rejected

> An invalid cron or timezone in create_schedule now returns the reason to the agent instead of an internal error, and Sunday crons obey the interval.

Source: <https://everruns.com/docs/changelog/2026-10-12-schedule-cron-errors-reach-agent/>

Date: 2026-10-12
Products: Platform, Cloud, Framework
Category: Fix
Pull request: everruns/everruns#4615

When an agent called `create_schedule` with an invalid cron expression or an unknown timezone, the tool failed with “Internal server error”, so the model could not tell what to fix and the server logged it as an error. The tool now returns the reason, such as `Invalid IANA timezone 'Mars/Base'`, and the agent can retry with a corrected schedule.

Standard 5-field crons that name weekdays by number, such as `0 18 * * 0` for Sunday evenings, are read the same way everywhere, including in embedded Framework schedules. The 5-minute minimum interval now also applies to them.

See [Session schedules](https://everruns.com/docs/capabilities/session-schedules/). [#4615](https://github.com/everruns/everruns/pull/4615)