Value cannot be null. (Parameter 'version')

After making recent updates on calamari and tentacle I’m getting this error.

The Tentacle version looks 0.0.0 on the server but actually 6.1.1531. See the screenshots below.

Hi @berk.toprakci,

Thanks for reaching out! I’m sorry to hear you are having trouble with this particular tentacle, but I’m happy to help take a look.

It looks like you also submitted a support ticket on this, so if you don’t mind I will reach out there with an update shortly.

Once we sort out the underlying issue I can also post the solution back to this thread so it’s available for others in the community as well.

Best regards,


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Kind Regards,


One more update just to clear this off if it works for you, another customer had this issue and he was pushing a package out to the tentacle.

He mentioned:

For this project the version is like 000.0-xxx_xxx and it was perfectly working prior the upgrade.
But, effectively I’ve simplified the version to 000.0-xxx and it’s deploying without errors now.

If you run into this error make sure your packages are compliant with SemVer V2.0. The issue with the customer in this comment was that underscores are not valid SemVer V2.0 characters according to their documentation.

Kind Regards,


Good morning @berk.toprakci

I have some good news for you this morning. Our engineers updated a GitHub Issue we were already working on. Originally the issue was for having letters at the start of Maven packages but due to a few customers having issues such as the one you were facing below the engineers have extended that GitHub issue out to other packages. Also, in addition to SemVer, package retention now supports other version formats. This means that underscores and forward slashes should now be accepted.

The fix for this is out in the builds on the GitHub issue but for convenience, I have included them below:




You can either upgrade when you are ready if you are running Octopus Server or if you are on our Octopus Cloud offering we can force an upgrade (if required) when it’s convenient for you, or you can wait until we upgrade you automatically in your maintenance window.

If you need further information on this please let me know.

Kind Regards,