Error retrieving backtest chart

Here’s how Trader can troubleshoot the error message:
"API Error Message: Error retrieving backtest chart, please try again later"

Common Causes and Solutions

1. Charting Quotas Exceeded

QuantConnect enforces strict limits on custom chart usage depending on your subscription tier:

• Free/Quant Researcher: 10 Series per backtest, max 4,000–8,000 data points per series.
• Higher tiers (Team, Institution, etc.): Higher quotas—but still limited.

If you exceed these quotas:

• The algorithm may stop executing plots, and your chart data might be truncated, leading to errors in chart retrieval.
• Watch for these log messages:
  • Exceeded maximum chart series count, new series will be ignored.
  • Exceeded maximum points per chart, data skipped

Solution:

• Audit your self.plot() or self.add_chart() usage:
  • Remove or combine rarely-used series.
  • Reduce sampling frequency or backtest duration.
  • Limit plotting in high-frequency loops.

2. Temporary Platform/Network Issues

This error can sometimes be transient (network blips or service hiccups).

Solution:

• Wait a few minutes and retry.
• Check QuantConnect status page or forums for any outages.

3. Chart/Series Name Conflicts

• Chart or Series names using special/reserved characters, or duplicated names, may cause retrieval errors.

Solution:

• Use simple, unique names for charts/series. Avoid special characters and reserved QC series names.

4. Excessive Custom Charts

• Too many unique charts or series overwhelms the QC charting infrastructure.

Solution:

• Prune or group similar plots; only plot what is necessary.

5. Algorithmic Bugs

• Infinite loops or exceptions in charting logic may disrupt chart output.

Solution:

• Check backtest logs for warnings/errors unrelated to plotting quotas.

Action Plan for Trader:

1. Check Backtest Logs for Warnings about Chart Quotas.
2. Ensure Chart and Series Counts Are Below Your Tier Limit.
   • Free/Quant Researcher: 10 charts/series, 4,000–8,000 data points per series.
3. Retry Later to rule out transient issues.
4. Simplify or Temporarily Remove Complex Chart Code to isolate the problem.
5. Use Simple, Unique Names for All Custom Charts/Series.
6. If Problem Persists, Contact Support with your algorithm/project details.

If you want, I can show you example code to keep custom chart usage within quotas or to check for quota limits in your algorithm. Just let me know!

Sources: Charting - QuantConnect.com, Results - QuantConnect.com, Results - QuantConnect.com