The actual error turned out to be a java.lang.NoSuchMethodError: org.apache.commons.io.IOUtils.byteArray(I)[B] error.
Such an error is related to conflicting Java libraries (between org.apache.commons.io-2.3.0.jar
and commons-io.commons-io-2.11.0.jar
). Removing the former resolved the issue.
Likely, this caused an action to fail, and therefore, no JSON was generated from the export, causing the error Morne mentioned.
Might be an issue with the security in your app. You need to debug the flow creating the excel export to see if the data is present. If it is present in the microflow then you’ll need to debug the java code to see what is going wrong. See https://docs.mendix.com/howto/monitoring-troubleshooting/debug-java-actions/
Another option could be to create a second export for a simple record that you are sure the user has access to the data. This way you can verify that it is not an issue with the java code itself but rather with the data.