Cannot open connection

Hi,

Recently we deployed a new application to the Production environment. But facing DB connectivity issues.
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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 was successfully connected to DB.
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Now the application starts working fine
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After some time I tried testing the UI and it is showing the 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.