DB Connection error

Hi,

Recently I have deployed a new application to Production environment. But facing DB connectivity issue.
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After creating the Data Source at Admin Console it shows Test Successful.
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and when I verified the Data Store, it is successfully connected to DB.
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Now the application starts working fine
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After some time I tried to login it is showing same error.
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I'm repeating the same steps to avoid the error.

Please help me in clearing the error.

Thank you.