Limited set of queries impacted by Cypher 25 issue

Update timeline

1. identified Jan 26, 2026, 07:26 PM UTC

   We have identified an issue that may affect a limited set of Cypher 25 queries for AuraDB Free, Professional and AuraDS. This may affect: - Queries using the conditional query WHEN in combination with a non-grouping aggregation over null values result in an incorrect number of rows returned. - Queries using NEXT can produce an unexpected variable not defined error in some instances. We are actively working on a fix and will update this page as more information becomes available.

2. identified Jan 27, 2026, 01:37 AM UTC

   We have identified a solution for this issue and will be rolling out in Aura. Once the update has been deployed we will update this tatus page.

3. identified Jan 27, 2026, 09:50 AM UTC

   We are rolling out the fix and will update you when this is completed.

4. monitoring Jan 27, 2026, 11:10 AM UTC

   The fix has rolled out to the affected components, we are now monitoring the situation at this time.

5. monitoring Jan 27, 2026, 02:51 PM UTC

   We are continuing to monitor the situation at this time.

6. resolved Jan 27, 2026, 03:58 PM UTC

   The fix has been fully deployed to all impacted instances. This incident is now resolved.

7. postmortem Jul 02, 2026, 04:22 AM UTC

   ## **What Happened** Neo4j commenced the deployment of version 2026.01.1 to Aura free instances at 07:49 AM UTC on January 26, 2026. Following the detection of query failures during internal testing, the rollout was halted before it reached Aura higher tiers. The failures occurred on conditional queries \(e.g. WHEN …THEN …\) after the planner phase to behave differently in the case of aggregation over null values. We identified the root cause and developed a resolution, which was integrated into version 2026.01.2. On January 27, 2026, we began deploying 2026.01.2 across Aura instances, successfully upgrading all affected environments to the corrected version ## How the service was affected Queries using WHEN in 2026.01.1 in combination with aggregation over null values get an incorrect number of rows returned. Queries using NEXT can in some instances produce an unexpected variable not defined error. This caused the rewritten query to behave differently in the case of aggregation over null values. The conditional query would need to receive incoming rows containing null values and be aggregating over the values without using a grouping. Customers received an incorrect result if they were using the conditional query construct in Cypher 25 \(see [https://neo4j.com/docs/aura/managing-instances/cypher-version/](https://neo4j.com/docs/aura/managing-instances/cypher-version/)\), an impact that was limited to a limited number of Aura instances. ## What are we doing now We have enhanced our testing procedures to ensure comprehensive coverage across all product areas. This includes the development of new test cases designed to address both identified issues and potential future scenarios. Furthermore, we have integrated Cypher query testing within Aura as a standard component of our regression testing suite. These checks are now mandatory stages within our Continuous Integration pipeline and staging environments prior to any production rollout.