The Shareplex upgrade fails with "Location '/SharePlex/prod' must be empty for new installation". This is not an attempt to install Shareplex afresh, but rather, an upgrade attempt from a built in Shareplex 6.x to a higher one. Hence the proddir is not empty. If an attempt is made to bypass the problem by specifying a new proddir and an existing vardir, the installation fails with the same error.
Could be a number of reasons.
A quick workaround is as follows:
1. Shutdown Shareplex.
2. Use new proddir and new vardir when installing Shareplex.
3. Install Shareplex but do not run ora_setup. Start sp_cop and issue "version full" from sp_ctrl to verify that the new version is installed and that it successfully starts.
4. Shutdown Shareplex once again, then use new proddir and existing vardir and restart Shareplex. If the upgrade is from one version to a higher version, say 6.x to 7.x, then run ora_setup after shutting down Shareplex and prior to using new proddir and existing vardir when restarting Shareplex.
This error is seen in Shareplex 6.0 and up. Moreover, these instructions only apply if there is a requirement to save the old proddir.