Why Your Molecular Extension Might Not Load in SAMSON (and How to Fix It)

One common frustration for molecular modelers using SAMSON is discovering that a SAMSON Extension fails to load at startup. This usually happens after installing a new Extension or updating the SAMSON platform. Fortunately, there’s a straightforward explanation for this behavior, and understanding it can save time and prevent unexpected headaches.

The Source of the Problem

At its core, the issue lies in compatibility between the version of SAMSON you have installed and the version of the Software Development Kit (SDK) that an Extension was built with. SAMSON uses semantic versioning, which means its version numbers look something like major.minor.patch.

For example, SAMSON version 1.7.8 has:

  • Major version: 1
  • Minor version: 7
  • Patch version: 8

How Extension Compatibility Works

When SAMSON starts, it checks each installed Extension to determine whether it was built using an SDK version that is compatible. The compatibility rules are very clear:

  • The major version number of SAMSON and the SDK used to build the Extension must be identical.
  • The SDK’s minor version number must be less than or equal to SAMSON’s minor version number.

So, if your version of SAMSON is 1.7.8:

  • An Extension built with SDK 1.3.5 or 1.7.7 will load.
  • An Extension built with SDK 1.8.5 will not load, because its minor version is greater.

This mechanism prevents situations where a newer Extension uses internal functions or features that your installed SAMSON version doesn’t support.

How to Avoid Compatibility Issues

The easiest way to avoid these version mismatches? Keep SAMSON up to date. SAMSON supports automatic updates of Extensions as long as:

  • You’re online at startup
  • The Extension was built with a compatible SDK

For instance, if you have SAMSON 1.7.8, and the Extension was originally built with SDK 1.5.2, SAMSON will load it. If a newer version built with SDK 1.6.4 becomes available on SAMSON Connect, it will be automatically updated—still compatible.

However, if developers begin publishing newer versions of their Extensions built with a brand-new SAMSON SDK version, like 2.0.0, and you haven’t updated SAMSON itself, the new Extension versions won’t work for you. Don’t worry, SAMSON will continue loading the older compatible version.

A Practical Takeaway

To molecular modelers dealing with multiple Extensions in their workflows, it’s essential to:

  • Regularly update SAMSON to get new features and fixes
  • Note the SDK version noted in your Extensions
  • Understand that backward compatibility works only in one direction

This simple practice keeps your environment stable and your modeling productive.

To learn more about version compatibility in SAMSON, you can read the full documentation at https://documentation.samson-connect.net/users/latest/versioning/.

SAMSON and all SAMSON Extensions are free for non-commercial use. You can get SAMSON at https://www.samson-connect.net.

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