Considerations
Using the MDB_ADO format in FME 2025.2 and older may cause FME Workbench to get stuck in a state of perpetual translation. Example below, when trying to add an MDB_ADO reader to FME Workbench, the issues are highlighted in orange with explanations:
- The translation will not end on its own. Clicking on Stop will cause an error message to appear, saying the translation failed.
- Log shows that the reader was successfully added to the workspace, though the FME session is still in progress. A similar issue occurs with Microsoft Access (ADO) readers in existing workspaces, where running the workspace will generate a log that reports that the FME translation was successful, yet FME Workbench itself shows the translation is still running.
At the point where the success message appears on the log, the workspace has finished executing its tasks, and it is safe to press the Stop button. Once clicked, FME will log an error message showing that the translation failed, but the process will already have completed. This will also affect existing workspaces that use the Microsoft Access ADO format.
Why This Happens
Microsoft introduced several consecutive security hardening updates beginning in January of 2026, which combined with the presence of the Office 365 Access Runtime, is the suspected underlying root cause of the issue.
The first update suspected of causing this issue is the Microsoft Security update from January 13 (KB5074109), but this behavior has persisted in all subsequent security updates.
The most common way it manifests itself is by keeping FME in a perpetual state of translation, with the data caches and workspace elements continuing to load even after a translation completes.
How to Resolve It
While the error with FME’s Microsoft Access ADO format may show slight differences depending on a user's environment, in particular, the system’s currently applied Microsoft security updates, the following options may help affected users find a resolution. These workarounds are presented in order of reliability, with the first option being the most reliable workaround:
- Switch to using the Microsoft Access JDBC reader and writer in your workspaces
- The Access JDBC reader and writer(MSACCESS_JDBC_2) has been tested thoroughly and will not cause the perpetual translation error
- Install Microsoft Access Database Engine 2016 Redistributable (no longer supported by Microsoft)
- Downloading and installing the driver will unblock Microsoft Access ADO format, but it is not recommended, as not only has it been deprecated by Microsoft, but any updates to Office will replace it with the Access 365 Runtime and cause the issue to reappear.
- Use FME 2026.1 or newer. Please note that FME 2026.1+ may not resolve the issue in certain environments or when executing FME translations via command line(CLI).