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If this is only from CI and not from DCO Bot, then please contact a Maintainer, as it probably means that the main branch has a commit that does not follow DCO which will necessitate a main rebase.
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Feel free to check out this tutorial for more help.
As per section 12.a of the Hyperledger Charter all code submitted to the Hyperledger Foundation needs to have a Developer Certificate of Origin (DCO) sign-off.
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