I found that sometimes loading Hveto page was failed.
I fixed this problem by changing the start time of the rerun process.

Detail:
Sometimes SummaryPage can't load Hveto html file by Ajax function of jQuery.
I use Chrome developer tool to find the error of this issue.
If html file could be loaded, index.html would specify the location of the symbolic link.
On the other hand, if html file could not be loaded, it specified the actual state of the file.
Next, I checked the configuration file and confirmed that the configuration file specifies the symbolic link.
Finally, I checked the gwsumm code and found that there is a process in the program to expand the symbolic link.
Both the Hveto and rerun processes run around 12 JST.
If the Hveto process finishes first, the rerun process is expected to expand the symbolic link.
So I changed the rerun process to run at 10:30.
I will see how it goes.