A molecular modeling workflow can depend on more than the structure on screen. It may also rely on SAMSON Extensions for particular tasks. When an extension does not load after a software update—or an extension update is unavailable—it is easy to wonder whether the extension is broken, outdated, or simply incompatible. Understanding SAMSON’s version numbers can help you narrow down the cause before you spend time troubleshooting the wrong thing.
Two version numbers, two different purposes
SAMSON has a public version and an internal version. The public version identifies the release users see; for example, the current public release listed in the documentation is 2026 R1. The internal version follows the three-part format major.minor.patch. That release is based on SAMSON and its SDK version 11.0.0.
The distinction matters because extensions are built with a particular version of the SAMSON Software Development Kit (SDK). SAMSON checks that SDK version when it starts and loads an extension only when its SDK version is compatible with the installed SAMSON version. An extension’s own version number is a separate matter: it can describe changes to that extension, but SAMSON uses the SDK version it was built with to decide compatibility.
The compatibility rule to check
Under SAMSON’s documented rule, an SDK version majorSDK.minorSDK.patchSDK is compatible with a SAMSON version majorSAMSON.minorSAMSON.patchSAMSON when:
- The major numbers are the same.
- The SDK minor number is smaller than SAMSON’s minor number.
For example, SDK versions 1.3.5 and 1.7.7 are compatible with SAMSON 1.7.8. SDK 1.8.5 is not: its minor number is higher than SAMSON’s. An extension built with that newer SDK might rely on functionality that does not exist in SAMSON 1.7.8.
One detail worth noticing: the documented comparison is based on the major and minor numbers, and the SDK minor must be smaller—not equal—to SAMSON’s. The patch numbers do not appear in this compatibility test. So comparing only the last number, or assuming that a numerically newer SDK is always suitable for an older SAMSON installation, can lead to the wrong conclusion.
A quick way to diagnose an extension issue
- Check the installed SAMSON version. Keep the public release label and internal version in mind; compatibility is described using the internal version.
- Find the SDK version used to build the extension. The extension’s own release number does not answer this compatibility question.
- Compare the major numbers. If they differ, the versions are not compatible under the documented rule.
- Compare the minor numbers. The SDK minor must be lower than SAMSON’s minor.
- Consider updates. SAMSON can automatically update extensions when compatible new versions are available on SAMSON Connect and an Internet connection is available.
This sequence helps separate two different situations: an extension may need an update that is compatible with your current SAMSON installation, or it may have been built for a different SAMSON SDK generation. Updating the extension alone cannot make an incompatible SDK version compatible with an older SAMSON release.
Why staying current can help
Suppose SAMSON 1.7.8 loads an extension built with SDK 1.5.2. If a compatible extension update built with SDK 1.6.4 becomes available on SAMSON Connect, SAMSON can install it automatically at startup, provided an Internet connection is available. But if SAMSON 2.0.0 and its SDK are released, an extension built for that new major version will not be a compatible update for someone still using SAMSON 1.7.8. In that case, the older compatible extension can remain in place until SAMSON is updated.
The practical takeaway is simple: when planning a software or extension update, check the SDK compatibility relationship—not just the extension’s displayed version. Keeping SAMSON updated also makes it more likely that compatible extension releases can be used.
For the complete versioning policy and additional examples, see the SAMSON versioning documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.