T2S Release 5.1 – Introduction on 20 September 2021 – Final update


Note: This announcement, originally published on 1 April and amended on 22 July 2021, has been further updated to provide customers with additional information on T2S Problem Tickets to be implemented with T2S Release 5.1. Changes are highlighted.  

Clearstream Banking AG, Frankfurt1 informs customers on the upcoming TARGET2-Securities (T2S) Release 5.1. According to the T2S Release Concept, the resolution for various T2S Problem Tickets (PBIs) will be deployed on

Saturday, 18 September 2021
for the business day Monday, 20 September 2021

T2S Release 5.1 - Scope

Based on the T2S status reporting of mid-August 2021, with T2S Release 5.1, the resolution of 16 Problem Tickets (PBIs) is envisaged for a delivery in production. CBF’s assessment shows that the fixes will not require any software changes in CBF.

The list of PBIs published by CBF on 22 July 2021 has been reviewed based on the new information. The analysis shows that a total of ten PBIs may have an impact on CBF customers operating in ICP and / or DCP mode. The attached updated list gives an overview of all PBIs that may be relevant for CBF customers.

In general, customers are recommended to validate these scope elements and check whether operational and / or functional modifications in their procedures are required.

T2S Release 5.1 – Transition plan

The Market Infrastructure Board (MIB) will decide on the deployment of T2S Release 5.1 in production once the expected results have been shown during testing. The final decision is to be made on Tuesday, 7 September 2021.

The deployment of T2S Release 5.1 into production is planned for business day Monday, 20 September 2021. The implementation of the software will take place during the weekend’s T2S maintenance window. Meaning that currently no changes in the T2S Operational Day are expected; neither for the end of day (EoD) procedure on Friday, 17 September 2021, nor for the start of business day, Monday, 20 September 2021.

The below table provides an overview of the upcoming T2S milestones:

T2S Service Transition Plan

Activity for T2S Release 5.1 


End of testing of scope elements in UTEST

Wednesday, 1 September 2021

Final approval of deployment to Production by MIB

Tuesday, 7 September 2021

Deployment to Production environment

Saturday, 18 September 2021

Customer simulation

The simulation activities will be conducted in a “free simulation mode”. The already established static data for CBF accounts and the related connectivity settings in the CBF customer simulation environment (IMS23) remain unchanged.

Irrespective of whether CBF has to modify its software, CBF will maintain its link to the T2S Pre-Production environment (UTEST) so that customers can test on their demand. 

Further information

For further information, customers may contact Clearstream Banking Client Services or their Relationship Officer. Questions related to the technical connection can be addressed to Connectivity Support. Particular questions related to the production launch in September 2021 will be routed to the experts of the T2S Release Management team.


1. This Announcement is published by Clearstream Banking AG (CBF), registered office at Mergenthalerallee 61, 65760 Eschborn, Germany, registered with the Commercial Register of the District Court in Frankfurt am Main, Germany, under number HRB 7500.