A SAMSON Extension that worked yesterday may not load after an update—or a newer extension may not appear to install. For molecular modelers, that can interrupt a workflow just when a project needs to be opened or continued. One useful first check is the version of the SAMSON SDK used to build the extension. SAMSON uses that version—not the extension’s own version number—to decide whether the extension is compatible.
Two version numbers, two different jobs
SAMSON has a public release number and an internal version number. The current public version listed in the documentation is 2026 R1, based internally on SAMSON and its SDK version 11.0.0. The internal version follows a major.minor.patch format. The public label helps identify the release; the internal number is relevant to compatibility.
An extension also has its own version number, such as 2.4.1. That number can tell you that the extension itself has changed, but it does not determine whether SAMSON can load it. For compatibility, SAMSON checks the SDK version that was used to build the extension.
The compatibility rule
For the standard semantic-versioning case described in the documentation, an extension built with SDK version majorSDK.minorSDK.patchSDK is compatible with SAMSON version majorSAMSON.minorSAMSON.patchSAMSON when:
- The SDK and SAMSON have the same major version.
- The SDK minor version is lower than SAMSON’s minor version.
The patch numbers do not appear in this compatibility test. For example, SDK 1.3.5 is compatible with SAMSON 1.7.8: the major versions match, and 3 is lower than 7. SDK 1.8.5 is not compatible with SAMSON 1.7.8, because its minor version is higher. An extension built with that newer SDK could rely on functionality that is not present in SAMSON 1.7.8.
This gives you a practical way to interpret a compatibility problem: compare the SDK version used to build the extension with the internal SAMSON version. A matching major number alone is not enough; the SDK minor version must also be lower. These examples illustrate the versioning rule and are not the current version numbers.
What happens when you update?
At startup, SAMSON checks each extension and loads it only if its SDK version is compatible. When an internet connection is available, SAMSON can also automatically update extensions to newer compatible versions published on SAMSON Connect.
For instance, the documentation describes SAMSON 1.7.8 loading an extension built with SDK 1.5.2. If a compatible update built with SDK 1.6.4 becomes available, SAMSON can update the extension at startup. But if SAMSON remains at 1.7.8 and a new extension version is built with SDK 2.0.0, SAMSON will not replace the compatible extension with that incompatible build. Updating SAMSON may be necessary before using an extension built for the new major SDK version.
A quick checklist before troubleshooting further
- Check SAMSON’s internal version, not only its public release label.
- Find the SDK version used to build the extension.
- Compare the major versions, then check that the SDK minor version is lower than SAMSON’s.
- Remember that the extension’s own version number describes the extension; it does not establish SDK compatibility.
- Keep SAMSON updated when practical, so compatible extension updates and fixes can be received.
This distinction can make an apparent extension problem easier to understand: the extension may be present and have a newer release number, yet still be incompatible with the installed SAMSON version. For the complete rules and examples, see the SAMSON versioning documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.