Pine Script Errors: How to Diagnose TradingView Code

A Pine Script problem can exist at several different layers. Some scripts fail to compile. Others compile but stop at runtime. Others run without an error message yet place the wrong trades, repaint signals, or produce results that do not match the trading idea.

The fastest debugging process is to identify which layer failed before changing the strategy itself.

1. Compiler errors

Compiler errors prevent the script from running at all. Common causes include incorrect function arguments, invalid syntax, undeclared variables, type mismatches, and code written for an older Pine Script version.

Start with the first compiler message rather than the last one. One early syntax problem can create several downstream errors that disappear once the first issue is corrected.

2. Runtime errors

A script can compile successfully and still fail while it runs on chart data. Runtime problems can come from invalid historical references, array operations, object limits, or calculations that encounter an unsupported state.

If TradingView marks the script with a runtime error, fix that before changing entry or exit rules.

3. Logic errors

Logic bugs are more difficult because the code may be perfectly valid. The script simply does something different from what you intended. A crossover can accidentally become a persistent “greater than” condition, an exit can run before an entry is eligible, or two filters can combine in a way that almost never becomes true.

For strategy code, compare each executable condition with the written trading rule. If you cannot describe the rule clearly outside the code, debugging becomes guesswork.

4. No trades or unexpected trades

An empty Strategy Tester is often not a compiler error at all. The strategy may have no reachable order command, insufficient simulated capital, an impossible entry condition, an overly restrictive date filter, or an open position that never exits.

If trades appear but in the wrong places, plot the component conditions temporarily and compare them with the final entry boolean.

5. Repainting and future-data problems

A script can look excellent on historical bars if it uses information that was not actually available when the historical decision would have been made. Multi-timeframe requests, pivot-style calculations, intrabar assumptions, and some visual signal techniques require special care.

The relevant question is not simply whether the code compiles. Ask whether the strategy uses only information that would have been available at the simulated decision point.

A disciplined debugging sequence

1. Save the original. Keep a clean copy before changing anything.
2. Fix compiler errors first. Work from the earliest reported error downward.
3. Resolve runtime failures. Make sure the script can process the loaded chart history.
4. Trace entry and exit booleans. Plot or log the conditions that actually control orders.
5. Compare code with the intended rules. Verify operators, thresholds, sequencing, and position state.
6. Review historical assumptions. Check timing, costs, sizing, multi-timeframe logic, and repaint risk.
7. Retest after one controlled change. Avoid changing several rules at once because that hides the actual fix.

What to include when asking someone to fix a script

• The complete Pine Script source, not only the line showing the error.
• The exact TradingView compiler or runtime message.
• What you expected the script to do.
• What it does instead.
• The symbol and timeframe if the behavior depends on them.
• A screenshot when the problem is visible on the chart or Strategy Tester.