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Users are unable to open records and tasks and the following error is seen in the application server log:
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
This issue has been addressed via AN-117715 in the following hotfixes/versions:
Revert the MySQL connector version to 5.1.46 or apply the latest hotfix to the environment.
1. 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'
2. Restart the application server
This article applies to Appian 18.1 and later.
Last Reviewed: November 2018