SLINT_INLINING has incorrect value. Must be either unset, 't

Error message

SLINT_INLINING has incorrect value. Must be either unset, 'true' or 'false'

What it means

Error "SLINT_INLINING has incorrect value. Must be either unset, 'true' or 'false'" thrown in slint-ui/slint.

Source

Thrown at internal/compiler/lib.rs:248

            let var = var.parse::<bool>().unwrap_or_else(|_|{
                panic!("SLINT_EMBED_RESOURCES has incorrect value. Must be either unset, 'true' or 'false'")
            });
            match var {
                true => EmbedResourcesKind::EmbedAllResources,
                false => EmbedResourcesKind::OnlyBuiltinResources,
            }
        } else {
            match output_format {
                #[cfg(feature = "rust")]
                OutputFormat::Rust => EmbedResourcesKind::EmbedAllResources,
                OutputFormat::Interpreter => EmbedResourcesKind::Nothing,
                _ => EmbedResourcesKind::OnlyBuiltinResources,
            }
        };

        let inline_all_elements = match std::env::var("SLINT_INLINING") {
            Ok(var) => var.parse::<bool>().unwrap_or_else(|_| {
                panic!(
                    "SLINT_INLINING has incorrect value. Must be either unset, 'true' or 'false'"
                )
            }),
            // Currently, the interpreter needs the inlining to be on.
            Err(_) => output_format == OutputFormat::Interpreter,
        };

        // The Slint SC generator flattens the exported component's element
        // tree, so user-defined components must be inlined away. This
        // overrides a SLINT_INLINING=false env override.
        #[cfg(feature = "slint-sc")]
        let inline_all_elements =
            inline_all_elements || matches!(output_format, OutputFormat::SlintSc);

        let const_scale_factor = std::env::var("SLINT_SCALE_FACTOR")
            .ok()
            .and_then(|x| x.parse::<f32>().ok())
            .filter(|f| *f > 0.);

View on GitHub (pinned to 3fd8f2ec03)

Solutions

Set SLINT_INLINING to 'true' or 'false', or unset it.
Remove any other value such as '1' or 'yes'.

When it happens

Trigger: Thrown at internal/compiler/lib.rs:248 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of slint-ui/slint@3fd8f2ec03 (2026-08-19). Data as JSON: /api/errors/d2e6ebc9e5d1833d. Report an issue: GitHub.