emake was unable to use the schedule data file indicated by [path] in the message because the file was corrupt. Specifically, the file header had the wrong values needed to mark it as valid emake scheduling data. When this warning appears, emake will not use schedule optimization, but will continue to execute the build as if the feature had not been enabled.
Although the schedule data file was found and was readable by emake, the content was invalid. This may be due to file corruption of some sort: the file may have been truncated, incompletely copied, or any of a host of other maladies.
When the build concludes, emake will recreate the schedule data file from scratch with valid data. Therefore in most cases no explicit user action is needed to correct the error. Alternatively, the user may remove the schedule data file indicated in the message, or avoid the issue by specifying a different --emake-assetdir, which would cause emake to use a different schedule file entirely.