A molecular modeling project can depend on more than its structure files. It may also rely on a SAMSON Extension—for example, a tool that supports a particular part of your workflow. If that Extension loads on one workstation but not another, or stops loading after a software change, the SDK version used to build it is one of the first things to check.
SAMSON checks Extension compatibility at startup. It compares the version of SAMSON installed on the computer with the version of the SAMSON SDK used to build the Extension. The Extension’s own version number does not determine whether SAMSON can load it.
Read the version numbers as a compatibility check
SAMSON and its SDK use three-part internal version numbers: major.minor.patch. According to the documented compatibility 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.
For example, an Extension built with SDK 1.5.2 can load in SAMSON 1.7.8: both have major version 1, and the SDK minor version 5 is lower than SAMSON’s 7. By contrast, SDK 1.8.5 is not compatible with SAMSON 1.7.8. The Extension may rely on functionality introduced in SDK 1.8 that is not available in SAMSON 1.7.
This gives you a practical first check when troubleshooting: confirm the SAMSON version, then find out which SDK version was used to build the Extension. Matching major versions alone is not enough; the minor-version condition matters too. Under the documented rule, patch numbers do not determine this compatibility check.
Why an Extension update may not arrive
SAMSON can automatically update Extensions when a newer compatible version is available on SAMSON Connect and an Internet connection is available. It will not install an Extension build that is incompatible with the SAMSON version on your computer.
For instance, SAMSON 1.7.8 can load an Extension built with SDK 1.5.2. If a compatible replacement built with SDK 1.6.4 is published, SAMSON can update to it at startup. But if the Extension developer publishes a build made with SDK 2.0.0, a user who remains on SAMSON 1.7.8 will not receive that incompatible build. The existing compatible Extension version can remain in use.
So, when an expected update does not appear, it does not necessarily mean the Extension has been removed or that automatic updating has failed. The newly published build may require a newer or different major version of SAMSON. Updating SAMSON regularly helps you receive compatible Extension updates, as well as SAMSON fixes and features.
Keep the two kinds of Extension version separate
An Extension also has its own major.minor.patch version, which its developer can use to describe changes to users. That is distinct from the SDK version used to build it. SAMSON uses the SDK version—not the Extension’s own version number—to decide whether the Extension can be loaded.
For teams sharing a modeling setup, recording the SAMSON version and the SDK version associated with required Extensions can make troubleshooting more straightforward. When a tool behaves differently across computers, those details help distinguish a compatibility issue from a difference in the molecular model or workflow.
The current public SAMSON release listed in the documentation is 2026 R1, based on internal version 11.0.0. To check the compatibility policy and current version information, see the SAMSON versioning documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON.