Summary
Security Token Service (STS) signing certificates can expire as soon as two years from the initial deployment
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, and if expired, it can cause users to be unable to log in to vSphere Client or the vmware-vpxd service to fail to start.
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To prevent this, it is recommended to replace the STS certificate if the expiration date is in less than 6 months.
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To replace the certificate, users can run the fixst script to regenerate the certificates.
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Additionally, users can try browser workarounds to access vCenter via the Flex client.
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According to
