diff --git a/src/server/editorServices.ts b/src/server/editorServices.ts
index 75ac31a7744..eb2249f85df 100644
--- a/src/server/editorServices.ts
+++ b/src/server/editorServices.ts
@@ -613,18 +613,23 @@ namespace ts.server {
                     // when creation inferred project for some file has added other open files into this project (i.e. as referenced files)
                     // we definitely don't want to delete the project that was just created
                     for (const f of this.openFiles) {
-                        if (f.containingProjects.length === 0) {
+                        if (f.containingProjects.length === 0 || !inferredProject.containsScriptInfo(f)) {
                             // this is orphaned file that we have not processed yet - skip it
                             continue;
                         }
-                        const defaultProject = f.getDefaultProject();
-                        if (isRootFileInInferredProject(info) && defaultProject !== inferredProject && inferredProject.containsScriptInfo(f)) {
-                            // open file used to be root in inferred project,
-                            // this inferred project is different from the one we've just created for current file
-                            // and new inferred project references this open file.
-                            // We should delete old inferred project and attach open file to the new one
-                            this.removeProject(defaultProject);
-                            f.attachToProject(inferredProject);
+
+                        for (const fContainingProject of f.containingProjects) {
+                            if (fContainingProject.projectKind === ProjectKind.Inferred &&
+                                fContainingProject.isRoot(f) &&
+                                fContainingProject !== inferredProject) {
+
+                                // open file used to be root in inferred project,
+                                // this inferred project is different from the one we've just created for current file
+                                // and new inferred project references this open file.
+                                // We should delete old inferred project and attach open file to the new one
+                                this.removeProject(fContainingProject);
+                                f.attachToProject(inferredProject);
+                            }
                         }
                     }
                 }
diff --git a/src/server/scriptInfo.ts b/src/server/scriptInfo.ts
index be3ef34ce3a..617b5a74999 100644
--- a/src/server/scriptInfo.ts
+++ b/src/server/scriptInfo.ts
@@ -261,10 +261,26 @@ namespace ts.server {
         }
 
         getDefaultProject() {
-            if (this.containingProjects.length === 0) {
-                return Errors.ThrowNoProject();
+            switch (this.containingProjects.length) {
+                case 0:
+                    return Errors.ThrowNoProject();
+                case 1:
+                    return this.containingProjects[0];
+                default:
+                    // if this file belongs to multiple projects, the first configured project should be
+                    // the default project; if no configured projects, the first external project should
+                    // be the default project; otherwise the first inferred project should be the default.
+                    let firstExternalProject;
+                    for (const project of this.containingProjects) {
+                        if (project.projectKind === ProjectKind.Configured) {
+                            return project;
+                        }
+                        else if (project.projectKind === ProjectKind.External && !firstExternalProject) {
+                            firstExternalProject = project;
+                        }
+                    }
+                    return firstExternalProject || this.containingProjects[0];
             }
-            return this.containingProjects[0];
         }
 
         registerFileUpdate(): void {
diff --git a/src/server/session.ts b/src/server/session.ts
index fd2e554d131..1ececa022b7 100644
--- a/src/server/session.ts
+++ b/src/server/session.ts
@@ -751,6 +751,17 @@ namespace ts.server {
             return projects;
         }
 
+        private getDefaultProject(args: protocol.FileRequestArgs) {
+            if (args.projectFileName) {
+                const project = this.getProject(args.projectFileName);
+                if (project) {
+                    return project;
+                }
+            }
+            const info = this.projectService.getScriptInfo(args.file);
+            return info.getDefaultProject();
+        }
+
         private getRenameLocations(args: protocol.RenameRequestArgs, simplifiedResult: boolean): protocol.RenameResponseBody | RenameLocation[] {
             const file = toNormalizedPath(args.file);
             const info = this.projectService.getScriptInfoForNormalizedPath(file);
@@ -758,7 +769,7 @@ namespace ts.server {
             const projects = this.getProjects(args);
             if (simplifiedResult) {
 
-                const defaultProject = projects[0];
+                const defaultProject = this.getDefaultProject(args);
                 // The rename info should be the same for every project
                 const renameInfo = defaultProject.getLanguageService().getRenameInfo(file, position);
                 if (!renameInfo) {
@@ -857,7 +868,7 @@ namespace ts.server {
             const file = toNormalizedPath(args.file);
             const projects = this.getProjects(args);
 
-            const defaultProject = projects[0];
+            const defaultProject = this.getDefaultProject(args);
             const scriptInfo = defaultProject.getScriptInfoForNormalizedPath(file);
             const position = this.getPosition(args, scriptInfo);
             if (simplifiedResult) {