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Users are unable to open records and tasks due to following error found in the application server logs:
Expression evaluation error in rule '<view_name>' (called by rule '<rule_name>') at function a!queryEntity [line 5]: An error occurred while retrieving the data. (APNX-1-4198-000)...Caused by: java.sql.SQLException: Illegal mix of collations for operation '<Operator_Name>'
Expression evaluation error in rule '<view_name>' (called by rule '<rule_name>') at function a!queryEntity [line 5]: An error occurred while retrieving the data. (APNX-1-4198-000)
...
Caused by: java.sql.SQLException: Illegal mix of collations for operation '<Operator_Name>'
For JBoss, server.log is located in the <JBOSS_HOME>/standalone/log directory. For Tomcat, tomcat-stdOut.log file is located in the <APPIAN_HOME>/log directory.
<JBOSS_HOME>/standalone/log
<APPIAN_HOME>/log
This error is witnessed when the MySQL connector version is changed to 5.1.47. This driver uses a different collation and characterEncoding setting compared to MySQL connector version 5.1.46 and lower.
For Appian version 18.2 and below, update the MySQL connector version to 5.1.46 via applying the latest hotfix.
For Appian version 18.3 modify the suite.xml file located in <APPIAN_HOME>/tomcat/apache-tomcat/conf/Catalina/localhost/ directory to support this collation via making the following changes to the connectionProperties field
<APPIAN_HOME>/tomcat/apache-tomcat/conf/Catalina/localhost/
connectionProperties='useUnicode=true;characterEncoding=UTF-8;connectionCollation=utf8mb4_unicode_ci'
This article applies to all versions of Appian.
Last Reviewed: October 2018