IT Release Schedule

Details of proposed changes to IESO systems and reports being revised for the current release are available here. Each release includes a preliminary, target and final planposted according to the IT Release Schedule. A yellow box indicates that the plan is not published for this release.

Target Release Plan

Final Release Plan

Release ID

R 44.1 R 45.0 R 45.1 R 46.0 R 46.1
Release Category Category 2 Category 3 Category 2 Category 3 Category 2
Real Time Production Build 2 Dec 2020 3 Mar 2020 2 Jun 2021 15 Sep 2021 1 Dec 2021
1. Preliminary Release Plan
19 Aug 2020 18 Nov 2020 17 Feb 2021 2 Jun 2021 18 Aug 2021
2. Market Participant Feedback
Period Ends
2 Sep 2020 2 Dec 2020 3 Mar 2021 16 Jun 2021 1 Sep 2021
3. Target Release Plan 16 Sep 2020 16 Dec 2020 17 Mar 2021 30 Jun 2021 15 Sep 2021
4. Final Release Plan 14 Oct 2020 13 Jan 2021 14 Apr 2021 28 Jul 2021 20 Oct 2021
5. Sandbox Implementation 22 Oct 2020 21 Jan 2021 22 Apr 2021 5 Aug 2021 28 Oct 2021
6(a). Production Build
(Non Real Time)
25 Nov 2020 24 Feb 2021 26 May 2021 8 Sep 2021 24 Nov 2021
6(b). Production Build
(Real Time)
2 Dec 2020 3 Mar 2021 2 Jun 2021 15 Sep 2021 1 Dec 2021

Four times per year, the IESO schedules a Preliminary Release Plan detailing upcoming changes to IESO systems that have been assessed to have an impact on participants. Comments on IT changes in the plan can be sent to Each release includes a preliminary, target and final plan, categorized as the following:

  • Category 3 releases (occurring twice a year) require market participants to make changes to their own technical interfaces with the IESO. Normally, significant system changes are the subject of stakeholder consultation well in advance of this release process.
  • Category 2 releases (occurring four times a year) require market participants to make a change in procedure or to update documentation, but not to modify any IT systems.
  • Category 1 releases do not have any impact on market participants and are managed through the IESO's internal release process. Market participants are notified only of any applicable outages, via the Planned IT Outages webpage.

Updates to the Preliminary Plan are added to the Target Release Plan, which is also open for comment by participants. New items are added to the Target Release Plan if required, and are posted through the IT Release Schedule.

The Final Release Plan is published one week in advance of the Sandbox implementation date, when changes are made available in the Sandbox environment for testing and training. Participants can contact IESO Customer Relations for more information if Sandbox access is required.

After the testing period is complete, the IESO will release the changes in Production, as shown on the IT Release Schedule. Accompanying documentation for the changes is available on Pending Changes – Documents as part of the baseline process.