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    Decryption Log Errors and Error Indexes
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    Decryption Log Errors and Error Indexes

    Table of Contents

    Decryption Log Errors and Error Indexes

    Learn, troubleshoot, and resolve certificate, cipher, protocol, version, and other TLS handshake errors you might find in a decryption log.
    Where Can I Use This?What Do I Need?
    No separate license required for decryption when using NGFWs or Prisma Access.
    Note: The features and capabilities available to you in Strata Cloud Manager depend on your active license(s).
    The Error Index and Error columns in decryption logs list error categories and details. You can also see error and error index information in the Handshake Details section of the Detailed Log View (click
    for any log entry). The Error Index column displays one of eight types of errors:
    If no suitable error category exists for an error, the default message is General TLS protocol error.
    • Certificate—Errors such as invalid certificates, expired certificates, unsupported client certificates, certificate revocation status check failures, and untrusted issuer CAs (sessions signed by an untrusted root, which includes incomplete certificate chains).
    • Cipher—Unsupported cipher errors where:
      • The client tries to negotiate a cipher that the NGFW supports but the decryption profile applied to the traffic doesn’t support.
      • The client tries to negotiate a cipher that the NGFW doesn’t support.
      • (Rare) Inbound Inspection is enabled and the server’s capabilities don’t match the decryption profile settings.
      • The error message includes the supported client cipher bitmask value and the supported decryption profile cipher bitmask value. You can use these values to identify the cipher the client tried to use and the ciphers that the decryption profile supports.
    • Feature—Errors such as oversized TLS handshakes or unknown handshakes, oversized certificate chains (more than five certificates), and other unsupported features.
    • HSM—Hardware storage module (HSM) errors such as unknown requests, items not found in the configuration, request timeouts, and other HSM errors and failures.
    • Protocol—Errors such as TLS handshake failures, private and public key mismatches, Heartbleed errors, TLS key exchange failures, and other TLS protocol errors. Protocol errors show when the server doesn’t support the protocols that the client supports, the server uses certificate types that the NGFW doesn’t support, and general TLS protocol errors.
    • Resource—Errors such as lack of sufficient memory.
    • Resume—Session resumption errors concerning resume session IDs and tickets, resume session entries in the NGFW cache, and other session resumption errors.
    • Version—Errors regarding client and decryption profile version mismatches and client and server version mismatches. The error messages include bitmask values that identify the supported client and decryption profile versions. You can use these values to identify the protocol version the client tried to use and the versions that the decryption profile supports.
    The following sections include a table that lists the specific errors for each error category along with additional information and resources. For some errors, possible remediation steps are shared. Finally, the Root Status “Uninspected” section describes why the Root Status column in a decryption log may display "uninspected."

    Certificate Errors

    Certificate errors are raised for reasons including invalid certificates, expired certificates, unsupported client certificates, Online Certificate Status Protocol (OCSP) or certificate revocation list (CRL) check failures, and untrusted issuer CAs (sessions signed by an untrusted root, which includes incomplete certificate chains).
    When the NGFW doesn’t have an intermediate certificate because the site didn't send the full certificate chain, you can find and install the missing certificate to repair an incomplete certificate chain.
    Decryption Error MessageAdditional Information and Resources
    Invalid (client or server) certificate
    Description: The certificate presented by either a client or server is invalid or cannot be verified.
    Related Documentation:
    Remediation:
    Expired (client or server) certificate
    Description: A certificate has expired or is not currently valid.
    RFC Information: This alert falls under the certificate_expired error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    Related Documentation:Troubleshoot Expired Certificates
    Remediation:
    Unsupported client certificate
    Description: The client certificate was of an unsupported type.
    RFC Information: This alert falls under the unsupported_certificate error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    OCSP / CRL check: certificate revoked
    Description: A certificate was revoked by its signer.
    RFC Information: This alert falls under the certificate_revoked error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    Related Documentation:
    Remediation:
    OCSP / CRL check failure
    Description: Sent by clients when an invalid or unacceptable OCSP response is provided by the server through the "status_request" extension.
    RFC Information: This alert falls under the bad_certificate_status_response error defined in RFC 8446, which is applicable to TLSv1.3.
    Untrusted issuer CA
    Description: A valid certificate chain was received, but the certificate authority (CA) certificate could not be matched with a known trust anchor.
    RFC Information: This alert falls under the unknown_ca error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    Related Documentation: Identify Untrusted CA Certificates
    Remediation: This error may be due to a configuration issue. Use a certificate from a trusted external CA (rather than an untrusted or self-signed CA). See Obtain a Certificate from an External CA.
    Received fatal alert <error name> from (client or server)
    Description: The variable error has caused the connection to fail.
    Server and firewall's certificate mismatch
    Description: The sender was unable to negotiate an acceptable set of security parameters with the receiver. A few possible causes are: incorrect certificates, a missing client certificate, an untrusted server certificate, or a missing server certificate.
    RFC Information: This alert falls under the handshake_failure error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    Remediation:
    SNI didn't match with subject name or SAN
    Related Documentation: SSL Decryption and Subject Alternative Names (SAN)
    General (client or server) certificate errorThis message indicates that an error doesn't meet the criteria for any of the aforementioned certificate errors.

    Cipher Errors

    Cipher errors are unsupported cipher errors where at least one of the following is true:
    • The client tries to negotiate a cipher that the NGFW supports but that the decryption profile applied to the traffic doesn’t support.
    • The client tries to negotiate a cipher that the NGFW doesn’t support.
    • (Rare) Inbound Inspection is enabled and the server’s capabilities don’t match the decryption profile settings.
    • The error message includes the supported client cipher bitmask value and the supported decryption profile cipher bitmask value. You can convert these values to actual values using operational CLI commands to identify the cipher the client tried to use and to list the cipher values that the decryption profile supports.
    Decryption Error MessageAdditional Information and Resources
    Unsupported cipher
    Description: The sender was unable to negotiate an acceptable set of security parameters with the receiver, likely due to incompatible cipher suites.
    RFC Information: This alert falls under the handshake_failure error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    Remediation:
    • Follow the steps to fix cipher errors.
    • Configure your decryption profiles such that the cipher suites selected are compatible with your sender and receiver's supported cipher suites. If needed, create a new decryption policy rule for the specific use case of your NGFW causing this issue.

    Feature Errors

    Feature errors include oversized TLS handshakes or unknown handshakes, oversized certificate chains (more than five certificates), and other unsupported features.
    Decryption Error MessageAdditional Information and Resources
    Client certificate received
    Related Documentation:
    Oversized chain (>5 certificates) received
    Description: The certificate chain contains more than five certificates.
    Remediation:
    Oversized handshake receivedN/A
    Unknown handshake message received
    Description: A field in the handshake was incorrect or inconsistent with other fields (albeit conforms to the formal protocol syntax), likely causing an unrecognizable handshake message.
    RFC Information: This alert falls under the illegal_parameter error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    Unsupported featureThis message indicates that an error doesn't meet the criteria for any of the aforementioned feature errors.

    HSM Errors

    Hardware storage module (HSM) errors include unknown requests, items not found in the configuration, request timeouts, and other HSM errors and failures.
    Decryption Error MessageAdditional Information and Resources
    Unknown requestN/A
    Certificate not found in configuration
    Remediation:
    Private key not found on HSM
    Remediation:
    • Store Private Keys on an HSM.
      • Verify that you successfully imported the certificate and private key used in your decryption deployment. Check the Key column for either a lock or error icon. The error icon indicates the private key is not on the HSM or the HSM is not properly authenticated or connected.
    • Restart the HSM.
    • Reset the HSM configuration. Select DeviceSetupHSM, and then Reset HSM Configuration from the Hardware Security Operations section.
    Request to HSM timed out
    Troubleshooting:
    • Verify NGFW connectivity and authentication with the HSM.
      • Select DeviceSetupHSM and look for a green dot next to Status. This indicates that the NGFW is successfully connected and authenticated to the HSM.
    Remediation:
    • Restart the HSM.
    • Reset the HSM configuration. Select DeviceSetupHSM, and then Reset HSM Configuration from the Hardware Security Operations section.
    HSM is down
    Related Documentation:
    Could not send request to HSM
    Related Documentation:
    Remediation: Restart the HSM.
    HSM server not found in configuration
    Related Documentation:
    General HSM failureThis message indicates that an error doesn't meet the criteria for any of the aforementioned HSM errors.

    Protocol Errors

    Protocol errors include TLS handshake failures, private and public key mismatches, Heartbleed errors, TLS key exchange failures, and other TLS protocol errors. Protocol errors show when the server doesn’t support the protocols that the client supports, the server uses certificate types that the NGFW doesn’t support, and general TLS protocol errors.
    Decryption Error MessageAdditional Information and Resources
    TLS Handshake Failure
    Description: The sender was unable to negotiate an acceptable set of security parameters with the receiver. A few possible causes are: incompatible cipher suites, incompatible SSL/TLS versions, incorrect certificates, missing client certificate, untrusted server certificate, or a missing server certificate.
    RFC Information: This alert falls under the handshake_failure error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    Remediation:
    Private key does not match public key
    Related Documentation:
    TLS Key Exchange Failure
    Description: The client and server are unable to exchange the keys needed to secure communication. A few possible causes are: incompatible cipher suites, incompatible SSL/TLS versions, or an incomplete certificate chain.
    Remediation:
    OpenSSL Error
    Description: An OpenSSL error was detected.
    Client only supports Post Quantum Algorithms
    Description: The TLS handshake failed because the client does not support classical algorithms.
    Related Documentation:
    General TLS Protocol Error
    This message indicates that an error doesn't meet the criteria for any of the aforementioned protocol errors.
    If no suitable error category exists for any error, this is the default error message.

    Resource Errors

    Resource errors point to a lack of sufficient memory.
    Decryption Error MessageAdditional Information and Resources
    Out of the firewall resources: memory
    Description: An internal error unrelated to the peer or SSL/TLS protocol correctness (such as a memory allocation error) makes it impossible to continue.
    RFC Information: This alert falls under the internal_errors error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    Out of the firewall resources (general)This message indicates that an error doesn't meet the criteria for any of the aforementioned resource errors.

    Resume Errors

    Resume errors include session resumption errors concerning resume session IDs and tickets, resumed session entries in the NGFW cache, and other session resumption errors.
    Decryption Error MessageAdditional Information and Resources
    No resume entry in firewall cache
    Description: The NGFW tried to resume a session for which a cache entry doesn't exist.
    General sessions resumption errorThis message indicates that an error doesn't meet the criteria for any of the aforementioned resume errors.

    Version Errors

    Version errors regard client and decryption profile version mismatches and client and server version mismatches. The error messages include bitmask values that identify the supported client and decryption profile versions. You can convert these values to actual values using operational CLI commands to identify the cipher the client tried to use and to list the cipher values that the decryption profile supports.
    Decryption Error MessageAdditional Information and Resources
    Client and decrypt profile version mismatch
    Description: The sender was unable to negotiate an acceptable set of security parameters with the receiver given the available options. This is likely due to incompatibility between the SSL/TLS versions supported by the client and in the decryption profile.
    RFC Information: This alert falls under the handshake_failure error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    Related Documentation: Troubleshoot Unsupported Cipher Suites
    Remediation:
    Client and server version mismatch
    Description: The sender was unable to negotiate an acceptable set of security parameters with the receiver given the available options. This is likely due to incompatibility between the SSL/TLS versions supported by the client and server.
    RFC Information: This alert falls under the handshake_failure error defined in RFC 5246, which is applicable to TLSv1.1-TLSv1.3.
    Related Documentation: Troubleshoot Unsupported Cipher Suites
    The troubleshooting topic uses the "Client and decrypt profile version mismatch" search query. For this error, use the (error contains ‘Client and server version mismatch’) query.
    Remediation:

    Root Status “Uninspected”

    In some cases, the Root Status column displays the value uninspected. Reasons why the NGFW might not inspect the root status include:
    • Session resumption
    • A decryption policy rule with an action of no-decrypt controls the traffic
    • A decryption failure occurs before the NGFW inspects the server certificate
    Filter the decryption log (root_status eq uninspected) and (tls_version eq TLS1.3) to see decryption sessions with a root status of "uninspected."

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