Some psaces don't open.

Dear Sir ,
WE have an issue that some spaces open normally without any delay or issue .

but we have some spaces its took time without open , and it give us an error message like if the tomcat down .

Service Temporarily Unavailable

The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

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Apache/2.2.3 (Red Hat) Server at hd.progressoft.com Port 80

in other hand when we open another space or the dashboard its open normally .

could you please advice its urgent please.