Condition step won't work correctly
I'm having a very frustrating issue with a condition step. In a previous step, I am setting a number of different variables. Here is an example from a run debug:
"metadata": {
"variables": {
"candidate_1_city": "Brooklyn",
"candidate_2_city": "Brooklyn",
"candidate_3_city": "Brooklyn",
"candidate_1_desired_schedule": "Part-time",
"candidate_2_desired_schedule": "Open to any work schedule",
"candidate_3_desired_schedule": "Per-Diem",
"candidate_1_state": "NY",
"candidate_2_state": "NY",
"candidate_3_state": "NY",
"candidate_1_languages": "English",
"candidate_2_languages": "English",
"candidate_3_languages": "English",
"candidate_1_discipline": "Personal Care Aide (PCA)",
"candidate_2_discipline": "Personal Care Aide (PCA)",
"candidate_3_discipline": "Personal Care Aide (PCA)",
"candidate_1_desired_shift": "Morning",
"candidate_2_desired_shift": "Evening; Afternoon; Weekdays; Morning; Night",
"candidate_3_desired_shift": "Morning; Afternoon; Evening; Night; Weekdays; Weekends",
"candidate_1_care_setting": "Inpatient; Home Care",
"candidate_2_care_setting": "Home Care; Inpatient",
"candidate_3_care_setting": "Home Care; Skilled (nursing / assisted living)",
"num_candidates": "3"
}
I have a condition step next which is looking to see if candidate_3_discipline is empty. I keep getting this error:
{
"time": 1756932611431,
"type": "debug",
"payload": {
"ref": {
"type": "node",
"nodeID": "68b8a539d07704ebfbd586ba",
"nodeType": "condition-v3",
"diagramID": "64dbb6696a8fab0013dba194"
},
"level": "warn",
"message": "expression failed",
"context": "Condition",
"metadata": {
"error": {}
}
}
}
I've tried doing this about 10 different ways with different variables but nothing is working.
1 Reply
That "expression failed" warning is coming from the JavaScript expression inside the Condition step – the code can’t be parsed, so the step never evaluates to true / false and Voiceflow shows the error.
A few things to double-check:
1️⃣ Make sure you write the variable name without curly-braces or quotes
2️⃣ The expression field must contain only a boolean expression – do not add a
return or a semicolon at the end.
3️⃣ If you prefer the no-code option, switch the Condition to Business Logic → Builder and set:
• Variable = candidate_3_discipline
• Operator = is empty
• Path = whatever you want to run when it’s empty
Voiceflow will create the correct JS for you in the background.
4️⃣ If there are executions where candidate_3_discipline hasn’t been created yet, the expression above (!candidate_3_discipline) will still work – an undefined or empty string is treated as falsey.
After fixing the expression / builder setup, run the Debugger again and the warning should disappear, with the flow taking the correct path.
Docs: https://docs.voiceflow.com (→ Condition step → Expression / Builder sections)