{"record":{"id":"270dc56de49f2aa3","repo":"DioxusLabs/dioxus","slug":"writer-checked","errorCode":null,"errorMessage":"writer checked","messagePattern":"writer checked","errorType":"panic","errorClass":null,"httpStatus":null,"severity":"error","filePath":"packages/core/src/diff/iterator.rs","lineNumber":548,"sourceCode":"        parent: Option<MountId>,\n        site: impl FnOnce(&mut Self) -> InsertionSite,\n        children: FragmentMountWriter,\n    ) -> usize {\n        self.create_children_at_site_with_mounts(new, parent, site, |dom, idx, mount| {\n            dom.set_mounted_fragment_child(children, idx, mount)\n        })\n    }\n\n    fn create_children_at_site_with_mounts(\n        &mut self,\n        new: &[VNode],\n        parent: Option<MountId>,\n        site: impl FnOnce(&mut Self) -> InsertionSite,\n        mut created_mount: impl FnMut(&mut VirtualDom, usize, MountId),\n    ) -> usize {\n        if self.has_writer() {\n            let site = site(self);\n            let to = self.to.as_deref_mut().expect(\"writer checked\");\n            site.create_and_place_with_result(to, self.dom.runtime.clone(), |to| {\n                let nodes = self.dom.create_children_with_mounts(\n                    Some(to),\n                    new,\n                    parent,\n                    |dom, idx, mount| {\n                        created_mount(dom, idx, mount);\n                    },\n                );\n                (nodes, nodes)\n            })\n        } else {\n            self.dom\n                .create_children_with_mounts(self.to.as_deref_mut(), new, parent, created_mount)\n        }\n    }\n}\n","sourceCodeStart":530,"sourceCodeEnd":566,"githubUrl":"https://github.com/DioxusLabs/dioxus/blob/24f6a829df0dfa203961a98ea4cae21c2ff27e28/packages/core/src/diff/iterator.rs#L530-L566","documentation":"Internal diffing invariant: the writer-presence flag was checked earlier in the call, so a writer must exist here. Firing indicates control-flow drift between has_writer checks and writer use in create_children_at_site_with_mounts.","triggerScenarios":"Thrown at packages/core/src/diff/iterator.rs:548 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["This is an internal diffing invariant (writer state). Report it with a minimal reproduction to the Dioxus issue tracker."],"exampleFix":null,"handlingStrategy":"type-guard","validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"24f6a829df0dfa203961a98ea4cae21c2ff27e28","analyzedAt":"2026-08-23T07:10:14.078Z","contentChangedAt":"2026-08-23T07:10:14.078Z","schemaVersion":2},"datasetVersion":"2026-09-14T00:17:10.932Z"}