diff --git a/crates/base-db/src/input.rs b/crates/base-db/src/input.rs
index c43941d6ac1..3a8c0c385a4 100644
--- a/crates/base-db/src/input.rs
+++ b/crates/base-db/src/input.rs
@@ -17,7 +17,7 @@ use vfs::{file_set::FileSet, AbsPathBuf, AnchoredPath, FileId, VfsPath};
 
 // Map from crate id to the name of the crate and path of the proc-macro. If the value is `None`,
 // then the crate for the proc-macro hasn't been build yet as the build data is missing.
-pub type ProcMacroPaths = FxHashMap<CrateId, Option<(Option<String>, AbsPathBuf)>>;
+pub type ProcMacroPaths = FxHashMap<CrateId, Result<(Option<String>, AbsPathBuf), String>>;
 pub type ProcMacros = FxHashMap<CrateId, ProcMacroLoadResult>;
 
 /// Files are grouped into source roots. A source root is a directory on the
diff --git a/crates/project-model/src/workspace.rs b/crates/project-model/src/workspace.rs
index 199fa1e5c2c..a6f1453582b 100644
--- a/crates/project-model/src/workspace.rs
+++ b/crates/project-model/src/workspace.rs
@@ -667,6 +667,14 @@ impl ProjectWorkspace {
             _ => false,
         }
     }
+
+    /// Returns `true` if the project workspace is [`Json`].
+    ///
+    /// [`Json`]: ProjectWorkspace::Json
+    #[must_use]
+    pub fn is_json(&self) -> bool {
+        matches!(self, Self::Json { .. })
+    }
 }
 
 fn project_json_to_crate_graph(
@@ -678,7 +686,7 @@ fn project_json_to_crate_graph(
     target_layout: TargetLayoutLoadResult,
 ) -> (CrateGraph, ProcMacroPaths) {
     let mut crate_graph = CrateGraph::default();
-    let mut proc_macros = FxHashMap::default();
+    let mut proc_macros: ProcMacroPaths = FxHashMap::default();
     let sysroot_deps = sysroot.as_ref().map(|sysroot| {
         sysroot_to_crate_graph(
             &mut crate_graph,
@@ -730,13 +738,11 @@ fn project_json_to_crate_graph(
             );
             if krate.is_proc_macro {
                 if let Some(path) = krate.proc_macro_dylib_path.clone() {
-                    proc_macros.insert(
-                        crate_graph_crate_id,
-                        Some((
-                            krate.display_name.as_ref().map(|it| it.canonical_name().to_owned()),
-                            path,
-                        )),
-                    );
+                    let node = Ok((
+                        krate.display_name.as_ref().map(|it| it.canonical_name().to_owned()),
+                        path,
+                    ));
+                    proc_macros.insert(crate_graph_crate_id, node);
                 }
             }
             (crate_id, crate_graph_crate_id)
@@ -1180,8 +1186,8 @@ fn add_target_crate_root(
     );
     if is_proc_macro {
         let proc_macro = match build_data.as_ref().map(|it| it.proc_macro_dylib_path.as_ref()) {
-            Some(it) => it.cloned().map(|path| Some((Some(cargo_name.to_owned()), path))),
-            None => Some(None),
+            Some(it) => it.cloned().map(|path| Ok((Some(cargo_name.to_owned()), path))),
+            None => Some(Err("crate has not yet been build".to_owned())),
         };
         if let Some(proc_macro) = proc_macro {
             proc_macros.insert(crate_id, proc_macro);
diff --git a/crates/rust-analyzer/src/cli/load_cargo.rs b/crates/rust-analyzer/src/cli/load_cargo.rs
index 268f59e7e4b..f644bdc7b18 100644
--- a/crates/rust-analyzer/src/cli/load_cargo.rs
+++ b/crates/rust-analyzer/src/cli/load_cargo.rs
@@ -102,7 +102,7 @@ pub fn load_workspace(
                 (
                     crate_id,
                     path.map_or_else(
-                        || Err("proc macro crate is missing dylib".to_owned()),
+                        |_| Err("proc macro crate is missing dylib".to_owned()),
                         |(_, path)| load_proc_macro(proc_macro_server, &path, &[]),
                     ),
                 )
diff --git a/crates/rust-analyzer/src/reload.rs b/crates/rust-analyzer/src/reload.rs
index 7b27a067062..c6bd3f0d9cc 100644
--- a/crates/rust-analyzer/src/reload.rs
+++ b/crates/rust-analyzer/src/reload.rs
@@ -251,7 +251,7 @@ impl GlobalState {
                     (
                         crate_id,
                         res.map_or_else(
-                            || Err("proc macro crate is missing dylib".to_owned()),
+                            |_| Err("proc macro crate is missing dylib".to_owned()),
                             |(crate_name, path)| {
                                 progress(path.display().to_string());
                                 load_proc_macro(
@@ -370,7 +370,7 @@ impl GlobalState {
         let files_config = self.config.files();
         let project_folders = ProjectFolders::new(&self.workspaces, &files_config.exclude);
 
-        if self.proc_macro_clients.is_empty() {
+        if self.proc_macro_clients.is_empty() || !same_workspaces {
             if let Some((path, path_manually_set)) = self.config.proc_macro_srv() {
                 tracing::info!("Spawning proc-macro servers");
                 self.proc_macro_clients = self
@@ -448,19 +448,8 @@ impl GlobalState {
         };
         let mut change = Change::new();
 
-        if same_workspaces {
-            if self.config.expand_proc_macros() {
-                self.fetch_proc_macros_queue.request_op(cause, proc_macro_paths);
-            }
-        } else {
-            // Set up errors for proc-macros upfront that we haven't run build scripts yet
-            let mut proc_macros = FxHashMap::default();
-            for paths in proc_macro_paths {
-                proc_macros.extend(paths.into_iter().map(move |(crate_id, _)| {
-                    (crate_id, Err("crate has not yet been build".to_owned()))
-                }));
-            }
-            change.set_proc_macros(proc_macros);
+        if self.config.expand_proc_macros() {
+            self.fetch_proc_macros_queue.request_op(cause, proc_macro_paths);
         }
         change.set_crate_graph(crate_graph);
         self.analysis_host.apply_change(change);