This message indicates that eMake failed to acquire a concurrent build license from the Cluster Manager, so eMake is unable to continue executing the build. eMake will wait in this state until a concurrent build license is available. Concurrent build licenses are allocated strictly in first come, first served order, so if multiple builds are waiting for a build license when a license becomes available, the waiting build with the lowest build id will receive the license and the others will continue to wait.
This warning does not indicate a build failure, but it does mean that the build will take longer to complete than normally expected.
This message means that there are more concurrent builds running than your CloudBees Build Acceleration license permits. Excess builds will simply queue until licenses become available.