A molecular modeling session can depend on more than the structure and the simulation settings. It may also depend on a SAMSON Extension used to prepare a system, inspect results, or support a particular workflow. When an extension does not load after an update—or stays behind while other software changes—the version numbers can be hard to interpret. SAMSON uses two different version labels, and extension compatibility depends on the internal one.
Two version numbers, two purposes
The public version is the release name users recognize, such as 2026 R1. The internal version follows the major.minor.patch format and is shared by SAMSON and its Software Development Kit (SDK). For example, SAMSON 2026 R1 is internally based on version 11.0.0.
This distinction matters because an extension is built against a particular SDK version. The public release label alone does not tell you which SDK was used to build it, so when checking compatibility, look for the internal version numbers.
The compatibility check in plain language
At startup, SAMSON checks the SDK version used to build each extension against its own internal version. According to the documented rule, an extension can load when the SDK and SAMSON have the same major version, and the SDK’s minor version is lower than SAMSON’s minor version. The patch numbers do not determine compatibility under this rule.
For example, an extension built with SDK 1.5.2 can be compatible with SAMSON 1.7.8: both use major version 1, and the SDK minor version, 5, is lower than SAMSON’s, 7. But an extension built with SDK 1.8.5 is not compatible with SAMSON 1.7.8, because its SDK minor version is higher. It may depend on functionality that the older SAMSON version does not have.
A useful first troubleshooting step is therefore to compare the internal SAMSON version with the SDK version used to build the extension—not just the extension’s own version number.
Why the extension’s version number is not enough
Each extension has its own major.minor.patch version. Developers can use that number to describe updates to their extension, but SAMSON does not use it to decide whether the extension can load. Compatibility is based on the SDK version used to build the extension. An extension with a higher extension version is not automatically compatible with every SAMSON release.
This is useful to keep in mind when comparing release notes or asking for help. Include both the SAMSON internal version and the extension’s build SDK version if you are investigating a loading issue.
What happens when an extension update is available?
SAMSON can automatically update extensions at startup when a newer compatible version is available on SAMSON Connect and an internet connection is available. The update is still subject to compatibility: SAMSON will not install an extension build that does not match its compatibility requirements.
For instance, if you continue using SAMSON 1.7.8, an extension built with SDK 1.6.4 can be updated for that installation because the major versions match and the SDK minor version is lower. If SAMSON later moves to a different major version, an extension built for that new major may not be usable in your older installation. Keeping SAMSON up to date helps you receive compatible extension releases, but it does not make builds for different major versions interchangeable.
A quick check before changing your setup
- Find SAMSON’s internal version as well as its public release name.
- Check the SDK version used to build the extension.
- Compare the major versions first. If they differ, the extension is not compatible under the documented rule.
- If the major versions match, compare the minor versions: the SDK minor version must be lower than SAMSON’s.
- Remember that the extension’s own version number describes its release, not its compatibility with SAMSON.
This small check can clarify whether a loading problem is likely a version mismatch before you change a working modeling environment. For the full policy and additional examples, see the SAMSON versioning documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.