diff --git a/.changeset/slimy-needles-taste.md b/.changeset/slimy-needles-taste.md
new file mode 100644
index 00000000000..7c6457818d2
--- /dev/null
+++ b/.changeset/slimy-needles-taste.md
@@ -0,0 +1,5 @@
+---
+'graphql-language-service-server': patch
+---
+
+Fix crash when editing a file that does not belong to a project
diff --git a/packages/graphql-language-service-server/src/GraphQLCache.ts b/packages/graphql-language-service-server/src/GraphQLCache.ts
index fcf578d42fd..7a3e0da2bdb 100644
--- a/packages/graphql-language-service-server/src/GraphQLCache.ts
+++ b/packages/graphql-language-service-server/src/GraphQLCache.ts
@@ -124,15 +124,14 @@ export class GraphQLCache implements GraphQLCacheInterface {
 
   getGraphQLConfig = (): GraphQLConfig => this._graphQLConfig;
 
-  getProjectForFile = (uri: string): GraphQLProjectConfig => {
+  getProjectForFile = (uri: string): GraphQLProjectConfig | void => {
     try {
       return this._graphQLConfig.getProjectForFile(URI.parse(uri).fsPath);
     } catch (err) {
       this._logger.error(
         `there was an error loading the project config for this file ${err}`,
       );
-      // @ts-expect-error
-      return null;
+      return;
     }
   };
 
diff --git a/packages/graphql-language-service-server/src/MessageProcessor.ts b/packages/graphql-language-service-server/src/MessageProcessor.ts
index 007d78f862f..4772d8f1058 100644
--- a/packages/graphql-language-service-server/src/MessageProcessor.ts
+++ b/packages/graphql-language-service-server/src/MessageProcessor.ts
@@ -665,7 +665,9 @@ export class MessageProcessor {
           await this._updateObjectTypeDefinition(uri, contents);
 
           const project = this._graphQLCache.getProjectForFile(uri);
-          await this._updateSchemaIfChanged(project, uri);
+          if (project) {
+            await this._updateSchemaIfChanged(project, uri);
+          }
 
           let diagnostics: Diagnostic[] = [];