@PIRASHATH88 After upgrading from PRPC-8.8.5-924 to INFINITY-24.2.0, the error indicates that the system is trying to use an older version of the PegaAppCA library (08-08) instead of the updated 24-01 version where the whatComesBeforeSubstring function exists. To resolve this, first ensure that the PegaAppCA:24-01 library is properly installed and included in your project’s classpath. Verify that all references in your configuration files point to the new version and remove any references to the old 08-08 version to prevent conflicts. Next, check that the whatComesBeforeSubstring utility function is correctly defined in the pegaappca_csutils and that there are no missing dependencies. After making these changes, clear any caches and restart the application server to ensure the new settings take effect. Additionally, review any customizations or extensions to ensure they are compatible with the new version. If the problem persists, consult the upgrade documentation for INFINITY-24.2.0 to identify any additional steps or compatibility issues. By ensuring that the correct library version is loaded and all configurations are updated accordingly, the error should be resolved, allowing the flow to run without issues.