Projects in Gerrit can be configured to require a Signed-off-by in the footer of the commit message to enforce that every change is signed by the author, committer or uploader. If for a project a Signed-off-by is required and the commit message footer does not contain it, Gerrit rejects to push the commit with this error message.
This policy can be bypassed by having the access right 'Forge Committer'.
This error may happen for different reasons if you do not have the access right to forge the committer identity:
missing Signed-off-by in the commit message footer
Signed-off-by is contained in the commit message footer but it’s neither from the author, committer nor uploader
Signed-off-by from the author, committer or uploader is contained in the commit message but not in the footer (last paragraph)
To be able to push your commits you have to update the commit messages as explained here so that they contain a Signed-off-by from the author, committer or uploader in the last paragraph. However it is important that you only add a Signed-off-by if you understand the semantics of the Signed-off-by and the commit applies to the rules that are connected with this footer.
Part of Gerrit Error Messages