diff --git a/crates/uv-workspace/src/pyproject.rs b/crates/uv-workspace/src/pyproject.rs
index 483169d7edf75..9e081ada2a7c9 100644
--- a/crates/uv-workspace/src/pyproject.rs
+++ b/crates/uv-workspace/src/pyproject.rs
@@ -94,6 +94,16 @@ impl PyProjectToml {
             .is_some_and(|project| project.version.is_none())
     }
 
+    /// Returns `true` if the key is set dynamically.
+    pub fn is_key_dynamic(&self, key: &str) -> bool {
+        self.project.as_ref().is_some_and(|project| {
+            project
+                .dynamic
+                .as_ref()
+                .is_some_and(|dynamic| dynamic.iter().any(|field| field == key))
+        })
+    }
+
     /// Returns whether the project manifest contains any script table.
     pub fn has_scripts(&self) -> bool {
         if let Some(ref project) = self.project {
@@ -221,6 +231,8 @@ pub struct Project {
     pub dependencies: Option<Vec<String>>,
     /// The optional dependencies of the project.
     pub optional_dependencies: Option<BTreeMap<ExtraName, Vec<String>>>,
+    /// The dynamic attributes of the project.
+    pub dynamic: Option<Vec<String>>,
 
     /// Used to determine whether a `gui-scripts` section is present.
     #[serde(default, skip_serializing)]
@@ -266,6 +278,7 @@ impl TryFrom<ProjectWire> for Project {
             requires_python: value.requires_python,
             dependencies: value.dependencies,
             optional_dependencies: value.optional_dependencies,
+            dynamic: value.dynamic,
             gui_scripts: value.gui_scripts,
             scripts: value.scripts,
         })
diff --git a/crates/uv-workspace/src/workspace.rs b/crates/uv-workspace/src/workspace.rs
index b974ab01832ba..90f2020a30492 100644
--- a/crates/uv-workspace/src/workspace.rs
+++ b/crates/uv-workspace/src/workspace.rs
@@ -8,7 +8,7 @@ use rustc_hash::FxHashSet;
 use tracing::{debug, trace, warn};
 use uv_distribution_types::Index;
 use uv_fs::{Simplified, CWD};
-use uv_normalize::{GroupName, PackageName, DEV_DEPENDENCIES};
+use uv_normalize::{ExtraName, GroupName, PackageName, DEV_DEPENDENCIES};
 use uv_pep440::VersionSpecifiers;
 use uv_pep508::{MarkerTree, VerbatimUrl};
 use uv_pypi_types::{
@@ -526,6 +526,38 @@ impl Workspace {
             .collect()
     }
 
+    /// Returns the set of all non-dynamic extras defined in the workspace.
+    pub fn extras(&self) -> BTreeSet<&ExtraName> {
+        self.pyproject_toml
+            .project
+            .as_ref()
+            .and_then(|project| project.optional_dependencies.as_ref())
+            .iter()
+            .flat_map(|extras| extras.keys())
+            .chain(
+                self.packages
+                    .values()
+                    .filter_map(|member| {
+                        member
+                            .pyproject_toml
+                            .project
+                            .as_ref()
+                            .map_or_else(|| None, |project| project.optional_dependencies.as_ref())
+                    })
+                    .flat_map(|extras| extras.keys()),
+            )
+            .collect()
+    }
+
+    /// Whether at least one project in the workspace sets the key dynamically.
+    pub fn uses_dynamic_key(&self, key: &str) -> bool {
+        self.pyproject_toml.is_key_dynamic(key)
+            || self
+                .packages
+                .values()
+                .any(|member| member.pyproject_toml.is_key_dynamic(key))
+    }
+
     /// The path to the workspace root, the directory containing the top level `pyproject.toml` with
     /// the `uv.tool.workspace`, or the `pyproject.toml` in an implicit single workspace project.
     pub fn install_path(&self) -> &PathBuf {
@@ -1573,7 +1605,8 @@ mod tests {
               "dependencies": [
                 "anyio>=4.3.0,<5"
               ],
-              "optional-dependencies": null
+              "optional-dependencies": null,
+              "dynamic": null
             },
             "pyproject_toml": "[PYPROJECT_TOML]"
           }
@@ -1588,7 +1621,8 @@ mod tests {
             "dependencies": [
               "anyio>=4.3.0,<5"
             ],
-            "optional-dependencies": null
+            "optional-dependencies": null,
+            "dynamic": null
           },
           "tool": null,
           "dependency-groups": null
@@ -1626,7 +1660,8 @@ mod tests {
                   "dependencies": [
                     "anyio>=4.3.0,<5"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               }
@@ -1641,7 +1676,8 @@ mod tests {
                 "dependencies": [
                   "anyio>=4.3.0,<5"
                 ],
-                "optional-dependencies": null
+                "optional-dependencies": null,
+                "dynamic": null
               },
               "tool": null,
               "dependency-groups": null
@@ -1679,7 +1715,8 @@ mod tests {
                         "bird-feeder",
                         "tqdm>=4,<5"
                       ],
-                      "optional-dependencies": null
+                      "optional-dependencies": null,
+                      "dynamic": null
                     },
                     "pyproject_toml": "[PYPROJECT_TOML]"
                   },
@@ -1693,7 +1730,8 @@ mod tests {
                         "anyio>=4.3.0,<5",
                         "seeds"
                       ],
-                      "optional-dependencies": null
+                      "optional-dependencies": null,
+                      "dynamic": null
                     },
                     "pyproject_toml": "[PYPROJECT_TOML]"
                   },
@@ -1706,7 +1744,8 @@ mod tests {
                       "dependencies": [
                         "idna==3.6"
                       ],
-                      "optional-dependencies": null
+                      "optional-dependencies": null,
+                      "dynamic": null
                     },
                     "pyproject_toml": "[PYPROJECT_TOML]"
                   }
@@ -1730,7 +1769,8 @@ mod tests {
                       "bird-feeder",
                       "tqdm>=4,<5"
                     ],
-                    "optional-dependencies": null
+                    "optional-dependencies": null,
+                    "dynamic": null
                   },
                   "tool": {
                     "uv": {
@@ -1796,7 +1836,8 @@ mod tests {
                     "bird-feeder",
                     "tqdm>=4,<5"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               },
@@ -1810,7 +1851,8 @@ mod tests {
                     "anyio>=4.3.0,<5",
                     "seeds"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               },
@@ -1823,7 +1865,8 @@ mod tests {
                   "dependencies": [
                     "idna==3.6"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               }
@@ -1886,7 +1929,8 @@ mod tests {
                   "dependencies": [
                     "tqdm>=4,<5"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               }
@@ -1901,7 +1945,8 @@ mod tests {
                 "dependencies": [
                   "tqdm>=4,<5"
                 ],
-                "optional-dependencies": null
+                "optional-dependencies": null,
+                "dynamic": null
               },
               "tool": null,
               "dependency-groups": null
@@ -2006,7 +2051,8 @@ mod tests {
                   "dependencies": [
                     "tqdm>=4,<5"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               },
@@ -2019,7 +2065,8 @@ mod tests {
                   "dependencies": [
                     "idna==3.6"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               }
@@ -2034,7 +2081,8 @@ mod tests {
                 "dependencies": [
                   "tqdm>=4,<5"
                 ],
-                "optional-dependencies": null
+                "optional-dependencies": null,
+                "dynamic": null
               },
               "tool": {
                 "uv": {
@@ -2109,7 +2157,8 @@ mod tests {
                   "dependencies": [
                     "tqdm>=4,<5"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               },
@@ -2122,7 +2171,8 @@ mod tests {
                   "dependencies": [
                     "idna==3.6"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               }
@@ -2137,7 +2187,8 @@ mod tests {
                 "dependencies": [
                   "tqdm>=4,<5"
                 ],
-                "optional-dependencies": null
+                "optional-dependencies": null,
+                "dynamic": null
               },
               "tool": {
                 "uv": {
@@ -2213,7 +2264,8 @@ mod tests {
                   "dependencies": [
                     "tqdm>=4,<5"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               },
@@ -2226,7 +2278,8 @@ mod tests {
                   "dependencies": [
                     "anyio>=4.3.0,<5"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               },
@@ -2239,7 +2292,8 @@ mod tests {
                   "dependencies": [
                     "idna==3.6"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               }
@@ -2254,7 +2308,8 @@ mod tests {
                 "dependencies": [
                   "tqdm>=4,<5"
                 ],
-                "optional-dependencies": null
+                "optional-dependencies": null,
+                "dynamic": null
               },
               "tool": {
                 "uv": {
@@ -2330,7 +2385,8 @@ mod tests {
                   "dependencies": [
                     "tqdm>=4,<5"
                   ],
-                  "optional-dependencies": null
+                  "optional-dependencies": null,
+                  "dynamic": null
                 },
                 "pyproject_toml": "[PYPROJECT_TOML]"
               }
@@ -2345,7 +2401,8 @@ mod tests {
                 "dependencies": [
                   "tqdm>=4,<5"
                 ],
-                "optional-dependencies": null
+                "optional-dependencies": null,
+                "dynamic": null
               },
               "tool": {
                 "uv": {
diff --git a/crates/uv/src/commands/project/export.rs b/crates/uv/src/commands/project/export.rs
index e60ede5b7e8b8..271fae9763e84 100644
--- a/crates/uv/src/commands/project/export.rs
+++ b/crates/uv/src/commands/project/export.rs
@@ -24,8 +24,8 @@ use crate::commands::project::install_target::InstallTarget;
 use crate::commands::project::lock::{do_safe_lock, LockMode};
 use crate::commands::project::lock_target::LockTarget;
 use crate::commands::project::{
-    default_dependency_groups, detect_conflicts, DependencyGroupsTarget, ProjectError,
-    ProjectInterpreter, ScriptInterpreter,
+    default_dependency_groups, detect_conflicts, ProjectError, ProjectInterpreter,
+    ScriptInterpreter, SpecificationTarget,
 };
 use crate::commands::{diagnostics, ExitStatus, OutputWriter};
 use crate::printer::Printer;
@@ -108,22 +108,23 @@ pub(crate) async fn export(
         ExportTarget::Project(project)
     };
 
-    // Validate that any referenced dependency groups are defined in the workspace.
+    // Validate that any referenced dependency groups and extras are defined in the workspace.
     if !frozen {
         let target = match &target {
             ExportTarget::Project(VirtualProject::Project(project)) => {
                 if all_packages {
-                    DependencyGroupsTarget::Workspace(project.workspace())
+                    SpecificationTarget::Workspace(project.workspace())
                 } else {
-                    DependencyGroupsTarget::Project(project)
+                    SpecificationTarget::Project(project)
                 }
             }
             ExportTarget::Project(VirtualProject::NonProject(workspace)) => {
-                DependencyGroupsTarget::Workspace(workspace)
+                SpecificationTarget::Workspace(workspace)
             }
-            ExportTarget::Script(_) => DependencyGroupsTarget::Script,
+            ExportTarget::Script(_) => SpecificationTarget::Script,
         };
-        target.validate(&dev)?;
+        target.validate_dependency_groups(&dev)?;
+        target.validate_extras(&extras)?;
     }
 
     // Determine the default groups to include.
diff --git a/crates/uv/src/commands/project/mod.rs b/crates/uv/src/commands/project/mod.rs
index d426435016874..53409bc3b6241 100644
--- a/crates/uv/src/commands/project/mod.rs
+++ b/crates/uv/src/commands/project/mod.rs
@@ -21,7 +21,7 @@ use uv_distribution_types::{
 use uv_fs::{Simplified, CWD};
 use uv_git::ResolvedRepositoryReference;
 use uv_installer::{SatisfiesResult, SitePackages};
-use uv_normalize::{GroupName, PackageName, DEV_DEPENDENCIES};
+use uv_normalize::{ExtraName, GroupName, PackageName, DEV_DEPENDENCIES};
 use uv_pep440::{Version, VersionSpecifiers};
 use uv_pep508::MarkerTreeContents;
 use uv_pypi_types::{ConflictPackage, ConflictSet, Conflicts, Requirement};
@@ -149,6 +149,15 @@ pub(crate) enum ProjectError {
     #[error("Default group `{0}` (from `tool.uv.default-groups`) is not defined in the project's `dependency-group` table")]
     MissingDefaultGroup(GroupName),
 
+    #[error("Extra `{0}` is not defined in the project's `optional-dependencies` table")]
+    MissingExtraProject(ExtraName),
+
+    #[error("Extra `{0}` is not defined in any project's `optional-dependencies` table")]
+    MissingExtraWorkspace(ExtraName),
+
+    #[error("PEP 723 scripts do not support optional dependencies, but extra `{0}` was specified")]
+    MissingExtraScript(ExtraName),
+
     #[error("Supported environments must be disjoint, but the following markers overlap: `{0}` and `{1}`.\n\n{hint}{colon} replace `{1}` with `{2}`.", hint = "hint".bold().cyan(), colon = ":".bold())]
     OverlappingMarkers(String, String, String),
 
@@ -1744,19 +1753,22 @@ pub(crate) async fn init_script_python_requirement(
 }
 
 #[derive(Debug, Copy, Clone)]
-pub(crate) enum DependencyGroupsTarget<'env> {
-    /// The dependency groups can be defined in any workspace member.
+pub(crate) enum SpecificationTarget<'env> {
+    /// The specification applies to any workspace member.
     Workspace(&'env Workspace),
-    /// The dependency groups must be defined in the target project.
+    /// The specification only applies to the target project.
     Project(&'env ProjectWorkspace),
-    /// The dependency groups must be defined in the target script.
+    /// The specification only applies to the target script.
     Script,
 }
 
-impl DependencyGroupsTarget<'_> {
+impl SpecificationTarget<'_> {
     /// Validate the dependency groups requested by the [`DevGroupsSpecification`].
     #[allow(clippy::result_large_err)]
-    pub(crate) fn validate(self, dev: &DevGroupsSpecification) -> Result<(), ProjectError> {
+    pub(crate) fn validate_dependency_groups(
+        self,
+        dev: &DevGroupsSpecification,
+    ) -> Result<(), ProjectError> {
         for group in dev
             .groups()
             .into_iter()
@@ -1788,6 +1800,77 @@ impl DependencyGroupsTarget<'_> {
         }
         Ok(())
     }
+
+    /// Validate the extras requested by the [`ExtrasSpecification`].
+    #[allow(clippy::result_large_err)]
+    pub(crate) fn validate_extras(self, extras: &ExtrasSpecification) -> Result<(), ProjectError> {
+        let extras = match extras {
+            ExtrasSpecification::Some(extras) => {
+                if extras.is_empty() {
+                    return Ok(());
+                }
+                extras
+            }
+            ExtrasSpecification::Exclude(extras) => {
+                if extras.is_empty() {
+                    return Ok(());
+                }
+                &Vec::from_iter(extras.clone())
+            }
+            _ => return Ok(()),
+        };
+
+        match self {
+            Self::Workspace(workspace) => {
+                // If at least one project in the workspace uses dynamic extras, the list of extras
+                // cannot be determined, so we cannot check if they are valid.
+                if workspace.uses_dynamic_key("optional-dependencies") {
+                    return Ok(());
+                }
+
+                let workspace_extras = workspace.extras();
+
+                for extra in extras {
+                    // The extra must be defined in the workspace.
+                    if !workspace_extras.contains(extra) {
+                        return Err(ProjectError::MissingExtraWorkspace(extra.clone()));
+                    }
+                }
+            }
+            Self::Project(project) => {
+                // If the project uses dynamic extras, the list of extras cannot be determined, so
+                // we cannot check if they are valid.
+                if project
+                    .current_project()
+                    .pyproject_toml()
+                    .is_key_dynamic("optional-dependencies")
+                {
+                    return Ok(());
+                }
+
+                let optional_dependencies = project
+                    .current_project()
+                    .pyproject_toml()
+                    .project
+                    .as_ref()
+                    .map_or_else(BTreeMap::new, |project| {
+                        project.clone().optional_dependencies.unwrap_or_default()
+                    });
+
+                for extra in extras {
+                    // The extra must be defined in the target project.
+                    if !optional_dependencies.contains_key(extra) {
+                        return Err(ProjectError::MissingExtraProject(extra.clone()));
+                    }
+                }
+            }
+            Self::Script => {
+                return Err(ProjectError::MissingExtraScript(extras[0].clone()));
+            }
+        }
+
+        Ok(())
+    }
 }
 
 /// Returns the default dependency groups from the [`PyProjectToml`].
diff --git a/crates/uv/src/commands/project/run.rs b/crates/uv/src/commands/project/run.rs
index 65ef8b76fb724..2f4a4301fcbc7 100644
--- a/crates/uv/src/commands/project/run.rs
+++ b/crates/uv/src/commands/project/run.rs
@@ -47,8 +47,8 @@ use crate::commands::project::install_target::InstallTarget;
 use crate::commands::project::lock::LockMode;
 use crate::commands::project::lock_target::LockTarget;
 use crate::commands::project::{
-    default_dependency_groups, validate_project_requires_python, DependencyGroupsTarget,
-    EnvironmentSpecification, ProjectError, ScriptInterpreter, WorkspacePython,
+    default_dependency_groups, validate_project_requires_python, EnvironmentSpecification,
+    ProjectError, ScriptInterpreter, SpecificationTarget, WorkspacePython,
 };
 use crate::commands::reporters::PythonDownloadReporter;
 use crate::commands::{diagnostics, project, ExitStatus};
@@ -683,21 +683,23 @@ pub(crate) async fn run(
                         .map(|lock| (lock, project.workspace().install_path().to_owned()));
                 }
             } else {
-                // Validate that any referenced dependency groups are defined in the workspace.
+                // Validate that any referenced dependency groups and extras are defined in the
+                // workspace.
                 if !frozen {
                     let target = match &project {
                         VirtualProject::Project(project) => {
                             if all_packages {
-                                DependencyGroupsTarget::Workspace(project.workspace())
+                                SpecificationTarget::Workspace(project.workspace())
                             } else {
-                                DependencyGroupsTarget::Project(project)
+                                SpecificationTarget::Project(project)
                             }
                         }
                         VirtualProject::NonProject(workspace) => {
-                            DependencyGroupsTarget::Workspace(workspace)
+                            SpecificationTarget::Workspace(workspace)
                         }
                     };
-                    target.validate(&dev)?;
+                    target.validate_dependency_groups(&dev)?;
+                    target.validate_extras(&extras)?;
                 }
 
                 // Determine the default groups to include.
diff --git a/crates/uv/src/commands/project/sync.rs b/crates/uv/src/commands/project/sync.rs
index 8558e07b4f78f..6ffc077721c70 100644
--- a/crates/uv/src/commands/project/sync.rs
+++ b/crates/uv/src/commands/project/sync.rs
@@ -32,7 +32,7 @@ use crate::commands::pip::operations::Modifications;
 use crate::commands::project::install_target::InstallTarget;
 use crate::commands::project::lock::{do_safe_lock, LockMode};
 use crate::commands::project::{
-    default_dependency_groups, detect_conflicts, DependencyGroupsTarget, ProjectError,
+    default_dependency_groups, detect_conflicts, ProjectError, SpecificationTarget,
 };
 use crate::commands::{diagnostics, project, ExitStatus};
 use crate::printer::Printer;
@@ -87,19 +87,20 @@ pub(crate) async fn sync(
         VirtualProject::discover(project_dir, &DiscoveryOptions::default()).await?
     };
 
-    // Validate that any referenced dependency groups are defined in the workspace.
+    // Validate that any referenced dependency groups and extras are defined in the workspace.
     if !frozen {
         let target = match &project {
             VirtualProject::Project(project) => {
                 if all_packages {
-                    DependencyGroupsTarget::Workspace(project.workspace())
+                    SpecificationTarget::Workspace(project.workspace())
                 } else {
-                    DependencyGroupsTarget::Project(project)
+                    SpecificationTarget::Project(project)
                 }
             }
-            VirtualProject::NonProject(workspace) => DependencyGroupsTarget::Workspace(workspace),
+            VirtualProject::NonProject(workspace) => SpecificationTarget::Workspace(workspace),
         };
-        target.validate(&dev)?;
+        target.validate_dependency_groups(&dev)?;
+        target.validate_extras(&extras)?;
     }
 
     // Determine the default groups to include.
diff --git a/crates/uv/src/commands/project/tree.rs b/crates/uv/src/commands/project/tree.rs
index fc9d274686f27..260ceb0d33b45 100644
--- a/crates/uv/src/commands/project/tree.rs
+++ b/crates/uv/src/commands/project/tree.rs
@@ -25,8 +25,8 @@ use crate::commands::pip::resolution_markers;
 use crate::commands::project::lock::{do_safe_lock, LockMode};
 use crate::commands::project::lock_target::LockTarget;
 use crate::commands::project::{
-    default_dependency_groups, DependencyGroupsTarget, ProjectError, ProjectInterpreter,
-    ScriptInterpreter,
+    default_dependency_groups, ProjectError, ProjectInterpreter, ScriptInterpreter,
+    SpecificationTarget,
 };
 use crate::commands::reporters::LatestVersionReporter;
 use crate::commands::{diagnostics, ExitStatus};
@@ -76,10 +76,10 @@ pub(crate) async fn tree(
     // Validate that any referenced dependency groups are defined in the target.
     if !frozen {
         let target = match &target {
-            LockTarget::Workspace(workspace) => DependencyGroupsTarget::Workspace(workspace),
-            LockTarget::Script(..) => DependencyGroupsTarget::Script,
+            LockTarget::Workspace(workspace) => SpecificationTarget::Workspace(workspace),
+            LockTarget::Script(..) => SpecificationTarget::Script,
         };
-        target.validate(&dev)?;
+        target.validate_dependency_groups(&dev)?;
     }
 
     // Determine the default groups to include.
diff --git a/crates/uv/tests/it/lock_conflict.rs b/crates/uv/tests/it/lock_conflict.rs
index a0143635f2cdb..c06a3bf098358 100644
--- a/crates/uv/tests/it/lock_conflict.rs
+++ b/crates/uv/tests/it/lock_conflict.rs
@@ -4413,11 +4413,17 @@ conflicts = [
         "#,
     )?;
 
-    // I believe there are multiple valid solutions here, but the main
-    // thing is that `x2` should _not_ activate the `idna==3.4` dependency
-    // in `proxy1`. The `--extra=x2` should be a no-op, since there is no
-    // `x2` extra in the top level `pyproject.toml`.
+    // Error out, as x2 extra is only on the child.
     uv_snapshot!(context.filters(), context.sync().arg("--extra=x2"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Extra `x2` is not defined in the project's `optional-dependencies` table
+    "###);
+
+    uv_snapshot!(context.filters(), context.sync(), @r###"
     success: true
     exit_code: 0
     ----- stdout -----
diff --git a/crates/uv/tests/it/sync.rs b/crates/uv/tests/it/sync.rs
index 9ee7cb2381671..b9bcaed8de55f 100644
--- a/crates/uv/tests/it/sync.rs
+++ b/crates/uv/tests/it/sync.rs
@@ -2402,6 +2402,88 @@ fn sync_group_self() -> Result<()> {
     Ok(())
 }
 
+#[test]
+fn sync_non_existent_extra() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+
+        [project.optional-dependencies]
+        types = ["sniffio>1"]
+        async = ["anyio>3"]
+        "#,
+    )?;
+
+    context.lock().assert().success();
+
+    // Requesting a non-existent extra should fail.
+    uv_snapshot!(context.filters(), context.sync().arg("--extra").arg("baz"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Extra `baz` is not defined in the project's `optional-dependencies` table
+    "###);
+
+    // Excluding a non-existing extra when requesting all extras should fail.
+    uv_snapshot!(context.filters(), context.sync().arg("--all-extras").arg("--no-extra").arg("baz"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Extra `baz` is not defined in the project's `optional-dependencies` table
+    "###);
+
+    Ok(())
+}
+
+#[test]
+fn sync_non_existent_extra_no_optional_dependencies() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        "#,
+    )?;
+
+    context.lock().assert().success();
+
+    // Requesting a non-existent extra should fail.
+    uv_snapshot!(context.filters(), context.sync().arg("--extra").arg("baz"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Extra `baz` is not defined in the project's `optional-dependencies` table
+    "###);
+
+    // Excluding a non-existing extra when requesting all extras should fail.
+    uv_snapshot!(context.filters(), context.sync().arg("--all-extras").arg("--no-extra").arg("baz"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Extra `baz` is not defined in the project's `optional-dependencies` table
+    "###);
+
+    Ok(())
+}
+
 /// Regression test for <https://github.com/astral-sh/uv/issues/6316>.
 ///
 /// Previously, we would read metadata statically from pyproject.toml and write that to `uv.lock`. In
@@ -4888,7 +4970,7 @@ fn sync_all_extras() -> Result<()> {
      + typing-extensions==4.10.0
     "###);
 
-    // Sync all extras.
+    // Sync all extras excluding an extra that exists in both the parent and child.
     uv_snapshot!(context.filters(), context.sync().arg("--all-packages").arg("--all-extras").arg("--no-extra").arg("types"), @r###"
     success: true
     exit_code: 0
@@ -4900,6 +4982,138 @@ fn sync_all_extras() -> Result<()> {
      - typing-extensions==4.10.0
     "###);
 
+    // Sync an extra that doesn't exist.
+    uv_snapshot!(context.filters(), context.sync().arg("--all-packages").arg("--extra").arg("foo"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Extra `foo` is not defined in any project's `optional-dependencies` table
+    "###);
+
+    // Sync all extras excluding an extra that doesn't exist.
+    uv_snapshot!(context.filters(), context.sync().arg("--all-packages").arg("--all-extras").arg("--no-extra").arg("foo"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: Extra `foo` is not defined in any project's `optional-dependencies` table
+    "###);
+
+    Ok(())
+}
+
+/// Sync all members in a workspace with dynamic extras.
+#[test]
+fn sync_all_extras_dynamic() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(
+        r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = ["child"]
+
+        [project.optional-dependencies]
+        types = ["sniffio>1"]
+        async = ["anyio>3"]
+
+        [build-system]
+        requires = ["setuptools>=42"]
+        build-backend = "setuptools.build_meta"
+
+        [tool.uv.workspace]
+        members = ["child"]
+
+        [tool.uv.sources]
+        child = { workspace = true }
+        "#,
+    )?;
+    context
+        .temp_dir
+        .child("src")
+        .child("project")
+        .child("__init__.py")
+        .touch()?;
+
+    // Add a workspace member.
+    let child = context.temp_dir.child("child");
+    child.child("pyproject.toml").write_str(
+        r#"
+        [project]
+        name = "child"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dynamic = ["optional-dependencies"]
+
+        [tool.setuptools.dynamic.optional-dependencies]
+        dev = { file = "requirements-dev.txt" }
+
+        [build-system]
+        requires = ["setuptools>=42"]
+        build-backend = "setuptools.build_meta"
+        "#,
+    )?;
+    child
+        .child("src")
+        .child("child")
+        .child("__init__.py")
+        .touch()?;
+
+    child
+        .child("requirements-dev.txt")
+        .write_str("typing-extensions==4.10.0")?;
+
+    // Generate a lockfile.
+    context.lock().assert().success();
+
+    // Sync an extra that exists in the parent.
+    uv_snapshot!(context.filters(), context.sync().arg("--all-packages").arg("--extra").arg("types"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 6 packages in [TIME]
+    Prepared 3 packages in [TIME]
+    Installed 3 packages in [TIME]
+     + child==0.1.0 (from file://[TEMP_DIR]/child)
+     + project==0.1.0 (from file://[TEMP_DIR]/)
+     + sniffio==1.3.1
+    "###);
+
+    // Sync a dynamic extra that exists in the child.
+    uv_snapshot!(context.filters(), context.sync().arg("--all-packages").arg("--extra").arg("dev"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 6 packages in [TIME]
+    Prepared 1 package in [TIME]
+    Uninstalled 1 package in [TIME]
+    Installed 1 package in [TIME]
+     - sniffio==1.3.1
+     + typing-extensions==4.10.0
+    "###);
+
+    // Sync dependencies, ignoring non-existing extras as the child uses dynamic extras.
+    uv_snapshot!(context.filters(), context.sync().arg("--all-packages").arg("--extra").arg("foo"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 6 packages in [TIME]
+    Uninstalled 1 package in [TIME]
+     - typing-extensions==4.10.0
+    "###);
+
     Ok(())
 }