---
bc-version: [20..]
domain: privacy
keywords: [strsubstno, error, telemetry, pii, prebuild, text-variable]
technologies: [al]
countries: [w1]
application-area: [all]
---

# Pass a Label directly as the first Error argument

## Description

Error method trace telemetry includes the AL error string only when the first `Error` argument is a `Label` or `TextConst`. Wrapping a label in `StrSubstNo`, or concatenating labels or text, produces a dynamic `Text` first argument. In that case the actual string is not emitted as the telemetry message; the platform emits its generic guidance instead. CodeCop AA0231 flags both shapes because the label identity and data-classification context are lost.

## Best Practice

Declare the complete message as a `Label` or `TextConst` and pass it directly to `Error`, followed by substitution values. The client receives the formatted message while telemetry retains the static message template without using the dynamic values as its message. Independently review whether each substitution value is appropriate to show to the current user.

See sample: `avoid-strsubstno-prebuild-before-error.good.al`.

## Anti Pattern

`Error(StrSubstNo(CustomerInvalidErr, Customer."No."))` and `Error(HeaderErr + DetailErr)` both make the first argument dynamic. They reduce error telemetry quality; they do not cause that composed string to be logged verbatim as the telemetry message.

See sample: `avoid-strsubstno-prebuild-before-error.bad.al`.