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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 than MySQL connector versions 5.1.46 and lower.
characterEncoding
Update the MySQL connector version to 5.1.46 or apply the latest hotfix to the environment.
Modify the suite.xml file located in the <APPIAN_HOME>/tomcat/apache-tomcat/conf/Catalina/localhost/ directory to support this collation by making the following changes to the connectionProperties field:
<APPIAN_HOME>/tomcat/apache-tomcat/conf/Catalina/localhost/
connectionProperties
connectionProperties='useUnicode=true;characterEncoding=UTF-8;connectionCollation=utf8mb4_unicode_ci'
This article applies to all versions of Appian.
Last Reviewed: October 2018