Symptom

Opening a Version file fails with an error message:
"Cannot read version file, as it was saved with newer Visum version."
How can I read data from Visum version files into older versions of Visum, i.e. from PTV Visum 2025 downgrading to PTV Visum 2024?

Cause

Version files use a binary format and are upward compatible, but not downward compatible.
That is, version files written by a particular version of Visum can be read by the same release version of Visum (regardless of the service pack) or newer versions, but not with older major versions.

Workaround

The following components of a Visum model can be saved to text-based files and read into a an older Visum version. However, warnings may appear indicating that some of the data could not be read.
- Network data as NET file.
- Matrices plus demand model as DMD file.
- Procedure parameters as XML file.
- Assignments cannot be ported directly, but you can copy volumes, travel times and queue lengths into user defined attributes and port them as ATT file.

Please note that assignment results may vary when exchanging the used release version (for example due to changes in the algorithm or because some procedure parameters are not understood by the older version). To monitor these, compare the values of main result attributes with the user defined attributes afterwards.

Reading binary files in the format before Visum 11.03 is no longer supported in PTV Visum 2022. In addition to version files, this also applies to graphic parameter files, procedure parameter files, list layouts
and filter files. You can use PTV Visum 2021 for this.