Workbench 2024 R2 project schema upgrade: is there any supported rollback path to 2023 R2?

Short answer

No. ANSYS does not document or support any downgrade mechanism for a Workbench project (.wbpj) once it has been saved under the 2024 R2 schema. The upgrade path is forward-only, and the only reliable rollback is restoring a pre-upgrade backup of the entire project directory. This is the well-established behavior for Workbench 2023 R2 / 2024 R2 on Windows; confirm against the Project Compatibility section of the 2024 R2 Release Notes for your exact build.

What actually happens when 2023 R2 opens a 2024 R2 project

Opening a newer-schema project in the older release triggers a schema-version mismatch warning, after which Workbench attempts to load the file anyway. The outcome is not deterministic from the outside:

• Systems that happen to use only constructs present in the 2023 R2 schema may load intact.
• Objects relying on 2024 R2-only features (new solver settings, result objects, parameter definitions) are dropped or replaced with incompatible-object placeholders.
• Some of this loss is silent — no error is raised, so a Mechanical or Fluent system can appear to open while missing parts of its physics setup or results.

Because of that last point, "it opened without errors" is not evidence the project survived.

Answering the three sub-questions

1. Supported downgrade? None exists. ANSYS support guidance consistently points to pre-upgrade backups as the rollback strategy. Exporting mesh/results to neutral formats (CDB, CGNS, Ensight) from 2024 R2 and re-importing into a fresh 2023 R2 project is a manual data-exchange workflow, not a project rollback — you lose schematic structure, parameters, and most settings.
2. Drop log or report? No structured, itemized report is produced. The message window and the Workbench journal (.wbjn) record generic schema-version and compatibility warnings, not a diff of dropped objects. You cannot query in advance which components will survive.
3. Per-system compatibility? No. The schema version is a property of the whole .wbpj file. Mechanical and Fluent systems inside it cannot be independently rolled back; partial survival is incidental, not a supported per-system mechanism.

Practical verification if you must attempt it

If no backup exists and you want to assess the damage rather than trust the load:

1. Copy the entire project directory first — .wbpj, the associated _files folder tree, and any linked external data. Never test the downgrade on the only copy.
2. Open the copy in 2023 R2 and record every message-window warning.
3. Compare system count, object counts within Mechanical/Fluent, and parameter counts against the 2024 R2 original to quantify what was dropped.
4. Search the journal file for schema and compatibility entries:

   findstr /I "SchemaVersion CompatibilityWarning incompatible" project_files\*.wbjn

5. Re-run or re-verify any system that loads, since silently dropped settings can produce plausible-but-wrong results.

Going forward

Treat the schema upgrade as a one-way gate: archive the full project directory before clicking through the upgrade prompt, or keep the project on 2023 R2 until all collaborators and downstream consumers have moved. If the project uses ACT extensions or custom scripts, the risk is higher — those frequently fail to load in the older release and can corrupt the project on save.

Uncertainty note: the absence of an itemized compatibility report and the forward-only policy reflect long-standing Workbench behavior; verify against the 2024 R2 Release Notes and your support channel before relying on this for a production project.