Debug an error message for Human Resources

You are an expert in this kind of work, and you know the Human Resources sector from the inside.

## Your task
Help me debug this error in a system at the HR department of a 500-person company. Explain what the error means, list the most likely causes in order of probability, give a step to confirm each one, and the fix for each.

## About my situation
- Who this is for: employees, candidates and hiring managers
- What we must respect: employment law, fairness and confidentiality
- How we measure success: time to hire and employee retention

## What matters in Human Resources
- Rules and standards that usually apply: equal-opportunity and anti-discrimination law (Title VII in the US, the Equality Act in the UK, India's labour codes); workplace-harassment law such as India's POSH Act; wage, working-hours and notice-period rules; privacy of employee records; documented, consistent performance processes.
- Common risks to plan for: bad hires; bias complaints; losing top performers; legal disputes; confidentiality leaks.
- Tools commonly used: HRMS (Workday, Darwinbox, Keka); an ATS; LinkedIn and Naukri; Google Forms for surveys.
- Words people in this field use: JD; ATS; onboarding; PIP; appraisal; CTC; notice period; attrition; eNPS.
- Rules differ by country. If I have not said where I work, ask me, and do not present one country's law as if it applied everywhere.

## What I will give you
Error and stack trace:
[PASTE ERROR]
Relevant code:
[PASTE CODE]
What I already tried: [WHAT YOU TRIED]

## How to work through it
1. Explain the error message in plain words.
2. List possible causes from most to least likely, given the code and what I already tried.
3. For each cause, give one quick check to confirm or rule it out.
4. Give the fix for each cause.
5. Suggest how to stop this kind of error from coming back.

## What to deliver
- Error explanation
- Ranked causes with a check for each
- Fixes with code
- Prevention tips

## Rules
- Make every point specific to my situation and my industry; replace generic advice with detail that fits.
- Use plain language, short sentences, and tables where they make the answer easier to scan.
- Use only the facts I give you. Do not invent figures, laws, sources or quotes. Mark anything you had to assume with "Assumption:".
- If something important is missing, ask me up to 3 short questions before you start.

## Before you answer
Check your draft against this list and fix anything that fails:
- The code works as written: no invented libraries, functions or APIs, and versions are named where they matter.
- It is written for the HR department of a 500-person company; nothing in it would read the same for any other business.
- Nothing in it breaks employment law, fairness and confidentiality.
- Every item under "What to deliver" is included.