+@pxref{gnus-agent-regenerate} command to fix possible problems.
+
+@node Agent Regeneration
+@subsection Agent Regeneration
+
+@cindex Agent Regeneration
+@cindex Gnus Agent Regeneration
+@cindex regeneration
+
+The local data structures used by @code{nnagent} may become corrupted
+due to certain exceptional conditions. When this happens,
+@code{nnagent} functionality may degrade or even fail. The solution
+to this problem is to repair the local data structures by removing all
+internal inconsistencies.
+
+For example, if your connection to your server is lost while
+downloaded articles into the agent, the local data structures will not
+know about articles downloaded prior to the connection failure.
+Running @code{gnus-agent-regenerate} or
+@code{gnus-agent-regenerate-group} will update the data structures
+such that you don't need to download these articles a second time.
+
+@findex gnus-agent-regenerate
+@kindex M-x gnus-agent-regenerate
+The command @code{gnus-agent-regenerate} will perform
+@code{gnus-agent-regenerate-group} on every agentized group. While
+you can run @code{gnus-agent-regenerate} in any buffer, it is strongly
+recommended that you first close all summary buffers.
+
+@findex gnus-agent-regenerate-group
+@kindex M-x gnus-agent-regenerate-group
+The command @code{gnus-agent-regenerate-group} uses the local copies
+of individual articles to repair the local NOV(header) database. It
+then updates the internal data structures that document which articles
+are stored locally. An optional argument will mark articles in the
+agent as unread.