Introduction

If you saw the phrase thinkorswum nan error in a search or on a chart, you are not alone. Seeing NaN or “Not a Number” in charts, labels, or custom scripts is a common problem when working with thinkorswim and thinkScript. This guide explains what NaN means, why it shows up, and how to fix it step by step. I keep the language simple and the actions practical. You’ll learn checks for the platform, data feed, chart settings, and thinkScript code. I also include quick fixes and safer coding patterns so NaN stops disrupting your work. Use this article as a one-stop reference to understand and fix the thinkorswum nan error.

What “NaN” Means and Why It Appears

NaN stands for “Not a Number.” It means the system expected a numeric value but did not get one. In thinkorswim and thinkScript, NaN often appears when a calculation cannot be completed. For example, trying to compute a moving average when there are not enough bars returns NaN. Another cause is a data gap—if the symbol has no quotes for the requested timeframe, the result can be NaN. The thinkorswim documentation explains how Double.NaN behaves and why it’s used in scripts to hide values that are undefined. Understanding that NaN is a placeholder helps you treat it as a signal, not a mysterious crash.

Where You Might See the thinkorswum nan error

You might see the thinkorswum nan error in chart plots, custom labels, watchlist columns, scanner results, or script-based studies. It can show up as a blank plot, an empty label, or a warning in the script console. NaN can also appear in folding errors when loops expect an integer but encounter undefined values. If you’re using indicators adapted from other sources, NaN is common until you check indexes, historical lookbacks, and symbol availability. The key first step is to note where NaN appears and whether it happens for one symbol, one timeframe, or across the platform. That pattern narrows down causes quickly.

Quick First Checks (fast fixes that often work)

Before you dive into code, try fast checks. Restart thinkorswim and see if the thinkorswum nan error persists. Clear the platform cache and reset the charts. Make sure the platform and your computer’s time and timezone are correct. Try switching to a different symbol and timeframe to see if NaN is symbol-specific. Also check for data-feed interruptions; sometimes missing quotes create NaN values. These quick steps often resolve transient glitches and are safe first moves before code changes. If the NaN stays after these checks, it’s time to inspect scripts and data more closely.

Understand the Data Problem: Look for Gaps and History Limits

A frequent cause of thinkorswum nan error is missing historical data. If a script requests 200 bars of history on a 1-minute chart but the chart only contains 50 bars, many functions will return NaN. The same happens if a secondary symbol has gaps or no quotes for the timeframe you chose. To test this, switch to a longer history or change aggregation periods. Use functions like to detect gaps so your script can handle them gracefully. Knowing your data limits avoids surprises and keeps scripts robust.

Code Causes: How thinkScript Produces NaN

In thinkScript, NaN often results from calculations that do not make mathematical sense, such as division by zero, square root of a negative number, or referencing future bars. Also, using intentionally hides plots when values are undefined. When you adapt code from other authors, be careful about folding loops and offsets that assume a minimum number of bars. Defensive coding—checking indexes and using—lets you avoid unintended NaN propagation. Treat NaN as a handled edge case rather than an error to panic about.

How to Use IsNaN() to Protect Your Scripts

The function is your friend when fixing a thinkorswum nan error in scripts. Use it to test values before using them in calculations. carry-forward techniques to substitute last-known good values where appropriate. Protecting code paths with checks prevents the NaN value from cascading through later math and plot statements. The official thinkScript docs and community examples show patterns for these checks.

Handling NaN in Indicators and Plots

If your indicator plots NaN where you expect data, give the plot either a valid value intentionally. Using hides the plot when no valid output exists, which is often useful for making charts cleaner. But if you need a numeric value for further math, replace NaN with a calculated fallback (like prior value or zero) only when that makes sense for your logic. A common pattern is which carries last-known values forward. Apply these patterns with care to avoid masking real problems.

Scanner and Watchlist NaN: Special Considerations

When NaN shows up in a scanner column or watchlist, it often means the formula tried to access a value not available for that symbol type or timeframe. For example, using a fundamental API on an intraday chart can return NaN because the fundamental data isn’t available by minute. In scans, be explicit about aggregation and use. to skip symbols with missing values. Community threads show many instances where NaN in scans is solved by checking symbol types or by adding fallback logic in the column formula. This approach prevents false negatives and empty columns.

Chart Settings and Aggregation Issues

Wrong aggregation settings can cause thinkorswum nan error to appear. If you plot a daily-based indicator on a tick or range chart, some inputs may not exist and return NaN. Verify your aggregation period and switch to a compatible timeframe when testing scripts. Also inspect the chart expansion and right-side time areas; plotting past or future values relative to the visible range can produce NaN. Fix aggregation mismatches and anchor offsets to visible history to reduce NaN occurrences. These checks are simple and often overlooked.

Server Limits and Subscription Constraints

Occasionally, NaN-like behavior is tied to platform limits or subscription tiers. Heavy custom calculations across many symbols can exceed client or server limits and produce invalid results. If your scripts request many cross-symbol values or perform heavy folding loops, consider reducing load or running the analysis on fewer symbols. The community notes and forum answers sometimes point to this as a cause. If you suspect server-side limits, contact thinkorswim support with logs and reproduction steps.

Debugging Workflow: Step-by-Step for Persistent NaN

If the thinkorswum nan error persists, follow a clear debug path. Reproduce the issue on a single symbol and timeframe. Isolate the smallest script that still produces NaN. lines to print intermediary values. Use checks to find the first NaN ancestor value. Test the script on symbols with long history and on bare charts to see if data gaps cause NaN. Once you find the root cause, add safeguards or adjust the logic. Keeping tests small speeds up troubleshooting and helps you learn what conditions cause NaN.

Practical Example: Fixing a Moving Average NaN

Imagine a 200-period moving average plugged into a 1-minute chart with only 100 bars visible; it returns NaN. Fix by either increasing the bar history or conditionally compute the MA only when enough bars exist:. Optionally, carry a simpler short MA forward as fallback. This pattern avoids the thinkorswum nan error and keeps indicators meaningful in short-history contexts. It’s a small change with big robustness payoff.

Script Folding, Loops, and NaN: Watch Your Iterations

When using constructs or loops in thinkScript, NaN can appear if the loop bounds are NaN or invalid. Folding expects integer bounds; if the computed bound is NaN, the engine complains. Protect fold bounds with checks and default integers. Avoid dynamic loop sizes computed directly from possibly-undefined values. Instead compute the bound with a safe fallback, validate, and then fold. This prevents hard-to-read NaN or folding errors in complex indicators. Community posts show this is a common gotcha when porting logic between platforms.

Platform Health: Cache, Update, and Reinstallation Steps

If code and data checks don’t fix the thinkorswum nan error, the platform itself might be in a bad state. Clear the thinkorswim cache, reset the app, and check for updates. If the problem began after an update, rollback or reinstall the platform. Keep backups of custom scripts before resetting. Many users report that cache problems or corrupted local files produce random NaN behavior that disappears after a fresh install or cache clear. Always try these platform-level steps as a last resort before changing complex scripts.

When to Contact Support and What to Send

If you reach out to thinkorswim or broker support, give them a clear reproduction case. Include the exact thinkorswum nan error text, the symbol, timeframe, script code snippet, and steps to reproduce. Attach a screenshot and the platform logs if possible. Mention whether the issue is isolated to one machine or account. Good bug reports speed resolution and help the support team identify server-side or data-feed problems faster. If you suspect a platform bug, logging precise steps is your best tool. Reddit

Best Practices to Avoid NaN Moving Forward

To reduce the chance of seeing the thinkorswum nan error again, adopt defensive coding and habits. Use checks, validate index ranges, and choose sensible fallbacks. Keep your scripts minimal and test them on different symbols and timeframes. Document assumptions like required bars of history. When sharing scripts, include notes about expected inputs and edge cases. For heavy computations, throttle the number of symbols or use scheduled offline tools. Small habits save time and avoid frustration when NaN appears.

Real User Tips and Community Wisdom

Community forums and threads are full of practical NaN fixes: replace undefined values with last-known values when appropriate; reduce server load by lowering refresh rates; and avoid querying unavailable fundamental data on intraday charts. Reading community threads helps you spot recurring patterns and shortcuts from experienced users. Pair those tips with official docs for the best results. The community also often shares small helper functions you can include in your scripts to handle NaN elegantly. Learning from others speeds debugging and improves your scripts faster.

FAQs (6 clear answers)

FAQ 1 — What exactly is the “thinkorswum nan error”?
The phrase thinkorswum nan error usually refers to seeing NaN (Not a Number) values or related warnings in thinkorswim. It can mean a plot is undefined, a calculation failed, or data was missing. NaN is a normal sentinel used to represent undefined numeric results. Fixing it means finding the missing input or protecting the calculation with checks.

FAQ 2 — Why does NaN happen only on some symbols?
NaN often appears on symbols with sparse quote data, newly-listed instruments, or those missing the requested timeframe history. Some API calls return NaN for certain asset types. Check symbol history, switch timeframes, or add defensive code that skips symbols with missing data.

FAQ 3 — Can clearing cache really fix it?
Yes. A corrupted cache or bad local state can cause strange NaN behavior. Clearing the thinkorswim cache or reinstalling the app has resolved persistent NaN and display issues for many users. Try cache clear after saving your scripts.

FAQ 4 — How do I handle NaN in scans and watchlists?
In scans and watchlist formulas, use to skip or mark symbols with missing values. Provide fallback values only if they make sense for the metric. That prevents empty columns and false alerts.

FAQ 5 — Is NaN always an error in my calculation?
Not always. NaN can be intentional to hide a plot). But unintended NaN usually signals a missing input or an impossible math operation. Treat it as a red flag to inspect assumptions.

FAQ 6 — When should I contact support vs. debug code?
If NaN appears across many symbols, after platform updates, or seems tied to data feeds, contact support with reproduction steps. If NaN is limited to a custom script or a specific indicator, debug code with checks and data-history tests first.

Conclusion

The thinkorswum nan error is usually fixable with a methodical approach. Start with quick platform checks, inspect data history and aggregation, then protect code with and safe fallbacks. For scanners and watchlists, validate symbol types and limit heavy cross-symbol queries. If platform-level issues persist, clear cache, reinstall, or contact support with a concise reproduction case. Using the defensive coding patterns and workflow shown here will make NaN less frustrating and easier to solve. If you want, I can review a short thinkScript snippet you’re using and suggest exact edits to remove NaN — paste the code and I’ll help clean it up.