How To Fix WEBDYNPRO_RT041 - Generation of secure random token failed

SAP Error Message - Details

• Message type: E = Error

• Message class: WEBDYNPRO_RT - Message class of Web Dynpro runtime

• Message number: 041

• Message text: Generation of secure random token failed

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message WEBDYNPRO_RT041 - Generation of secure random token failed ?

  The SAP error message WEBDYNPRO_RT041: Generation of secure random token failed typically occurs in the context of SAP Web Dynpro applications, especially when dealing with security tokens used for session management, CSRF protection, or other security-related features.
  
  Cause
  
  
  Insufficient Entropy / Randomness Source:
  
  The error indicates that the system failed to generate a secure random token. This usually happens because the underlying system's entropy pool (randomness source) is insufficient or blocked. Secure tokens require high-quality randomness, and if the entropy source is depleted or inaccessible, token generation fails.
  
  
  Operating System / Kernel Issues:
  
  On Unix/Linux systems, SAP relies on /dev/random or /dev/urandom for entropy. If /dev/random is blocking due to low entropy, or if the system's random number generator is malfunctioning, the token generation fails.
  
  
  Java Cryptography / Security Provider Issues:
  
  Since Web Dynpro applications run on the SAP NetWeaver Java stack, problems with the Java SecureRandom implementation or security providers can cause this error.
  
  
  Incorrect System Configuration:
  
  Misconfiguration of the SAP Java stack or the underlying OS security settings can lead to this problem.
  
  
  
  Solution
  
  
  Check System Entropy:
  
  On Linux/Unix, check the available entropy:
  cat /proc/sys/kernel/random/entropy_avail
  If the value is low (e.g., below 100), the system may not have enough entropy.
  
  
  
  
  Use Non-blocking Random Source:
  
  Configure the Java Virtual Machine (JVM) to use /dev/urandom instead of /dev/random to avoid blocking:
  
  Add the following JVM parameter to the SAP Java stack startup:
  -Djava.security.egd=file:/dev/./urandom
  
  The extra ./ is intentional to force the JVM to treat it as a non-blocking entropy source.
  
  
  
  
  
  Install or Configure Entropy Daemons:
  
  Install entropy-generating daemons like haveged or rng-tools to increase the entropy pool:
  sudo apt-get install haveged
  sudo systemctl start haveged
  sudo systemctl enable haveged
  
  This helps maintain sufficient entropy for secure random number generation.
  
  
  
  Check Java Security Providers:
  
  Verify that the Java security providers are correctly configured in the java.security file.
  Ensure no custom or faulty security providers are causing issues.
  
  
  
  Restart SAP Java Stack:
  
  After making changes, restart the SAP Java stack to apply the new JVM parameters or system configurations.
  
  
  
  SAP Notes and Patches:
  
  Check SAP Notes for any known issues or patches related to this error.
  For example, SAP Note 2345678 (example number) might provide specific fixes or recommendations.
  
  
  
  
  Related Information
  
  
  SAP Web Dynpro Security:
  
  Secure random tokens are used for CSRF protection and session management in Web Dynpro applications.
  
  
  Java SecureRandom:
  
  The Java class java.security.SecureRandom is used to generate cryptographically strong random numbers.
  
  
  Entropy in Linux:
  
  Linux systems use entropy pools to provide randomness. Low entropy can cause blocking reads on /dev/random.
  
  
  SAP Java Stack JVM Parameters:
  
  JVM parameters can be set in the SAP Java stack profile or startup scripts.
  
  
  SAP Community and Support:
  
  Searching SAP Community forums or opening a support ticket with SAP can provide additional help.
  
  
  
  Summary
  
  
  
  Aspect
  Details
  
  
  
  
  Cause
  Insufficient system entropy or misconfiguration causing failure in secure token generation
  
  
  Solution
  Increase system entropy, configure JVM to use /dev/urandom, install entropy daemons, restart SAP Java stack
  
  
  Related Info
  Java SecureRandom, Linux entropy, SAP Web Dynpro security, SAP Notes and patches
  
  
  
  
  If you continue to face issues after applying these solutions, consider collecting system logs, JVM logs, and SAP traces and contacting SAP Support for further assistance.