ProxySG sometimes shows the message "Failed to get session pointer" in eventlog. What does it mean and what is the impact?
On the SSL stream to the upstream SSL(web) server from the proxySG, ProxySG can cache "SSL sessions" to reuse them. A client request would try to use the cached session but the session does not exist then the message shows.
ProxySG 6.7 and later.
Reverse Proxy deployment is more likely to show this message, because SSL session caching in the reverse proxy will be used more than Forward proxy. See this KB for your assistance.
How does the proxy handle SSL session IDs in a reverse proxy environment
Basically this can be ignored as above explanation of the cause. There are no impacts on this because if SSL session is not exist, ProxySG can create a new session.