diff --git a/src/harness/incrementalUtils.ts b/src/harness/incrementalUtils.ts
index 47114c88d51..55301c7ec61 100644
--- a/src/harness/incrementalUtils.ts
+++ b/src/harness/incrementalUtils.ts
@@ -448,17 +448,25 @@ function verifySet(
     expected?.forEach(expected =>
         ts.Debug.assert(
             actual?.has(expected),
-            `${caption}:: Expected should be present in actual`,
+            `${caption}:: ${expected} should be present in actual`,
         )
     );
     actual?.forEach(actual =>
         ts.Debug.assert(
             expected?.has(actual),
-            `${caption}:: Actual should be present in expected`,
+            `${caption}:: ${actual} should be present in expected`,
         )
     );
 }
 
+function verifyArray(
+    expected: readonly string[] | undefined,
+    actual: readonly string[] | undefined,
+    caption: string,
+) {
+    return verifySet(expected && new Set(expected), actual && new Set(actual), caption);
+}
+
 function verifyProgram(service: ts.server.ProjectService, project: ts.server.Project) {
     if (service.serverMode === ts.LanguageServiceMode.Syntactic) return;
     const options = project.getCompilerOptions();
@@ -572,6 +580,24 @@ function verifyProgram(service: ts.server.ProjectService, project: ts.server.Pro
     verifyResolutionCache(project.resolutionCache, project.getCurrentProgram()!, resolutionHostCacheHost, project.projectName);
 }
 
+function verifyUnresolvedImports(_service: ts.server.ProjectService, project: ts.server.Project) {
+    const cachedUnresolvedImportsPerFile = new Map<ts.Path, readonly string[]>();
+    const lastCachedUnresolvedImportsList = project.useTypingsFromGlobalCache() ?
+        ts.server.getUnresolvedImports(project.getCurrentProgram()!, cachedUnresolvedImportsPerFile, ts.noop) :
+        undefined;
+    verifyArray(
+        lastCachedUnresolvedImportsList,
+        project.lastCachedUnresolvedImportsList,
+        `${project.getProjectName()}:: lastCachedUnresolvedImportsList`,
+    );
+    verifyMap(
+        cachedUnresolvedImportsPerFile,
+        project.cachedUnresolvedImportsPerFile,
+        (expected, actual, caption) => verifyArray(expected, actual, caption),
+        `${project.getProjectName()}:: cachedUnresolvedImportsPerFile`,
+    );
+}
+
 interface ResolveSingleModuleNameWithoutWatchingData {
     resolutionToData: Map<ts.ResolutionWithFailedLookupLocations, Pick<ts.ResolvedModuleWithFailedLookupLocations, "failedLookupLocations" | "affectingLocations" | "resolutionDiagnostics">>;
     packageJsonMap: Map<ts.Path, ts.PackageJsonInfoCacheEntry> | undefined;
@@ -648,6 +674,7 @@ export interface IncrementalVerifierCallbacks {
 export function incrementalVerifier(service: ts.server.ProjectService): void {
     service.verifyDocumentRegistry = withIncrementalVerifierCallbacks(service, verifyDocumentRegistry);
     service.verifyProgram = withIncrementalVerifierCallbacks(service, verifyProgram);
+    service.verifyUnresovedImports = withIncrementalVerifierCallbacks(service, verifyUnresolvedImports);
     service.onProjectCreation = onProjectCreation;
 }
 
diff --git a/src/server/editorServices.ts b/src/server/editorServices.ts
index 23f8d844c98..3b260b15d0e 100644
--- a/src/server/editorServices.ts
+++ b/src/server/editorServices.ts
@@ -1424,6 +1424,7 @@ export class ProjectService {
     /** @internal */ baseline: (title?: string) => void = noop;
     /** @internal */ verifyDocumentRegistry: typeof noop = noop;
     /** @internal */ verifyProgram: (project: Project) => void = noop;
+    /** @internal */ verifyUnresovedImports: (project: Project) => void = noop;
     /** @internal */ onProjectCreation: (project: Project) => void = noop;
     /** @internal */ canUseWatchEvents: boolean;
 
diff --git a/src/server/project.ts b/src/server/project.ts
index 85b1d08f96d..f3f8026a9a2 100644
--- a/src/server/project.ts
+++ b/src/server/project.ts
@@ -1418,6 +1418,13 @@ export abstract class Project implements LanguageServiceHost, ModuleResolutionHo
         updateProjectIfDirty(this);
     }
 
+    /** @internal */
+    useTypingsFromGlobalCache(): boolean {
+        return this.languageServiceEnabled &&
+            this.projectService.serverMode === LanguageServiceMode.Semantic &&
+            !this.isOrphan();
+    }
+
     /**
      * Updates set of files that contribute to this project
      * @returns: true if set of files in the project stays the same and false - otherwise.
@@ -1440,7 +1447,7 @@ export abstract class Project implements LanguageServiceHost, ModuleResolutionHo
 
         // update builder only if language service is enabled
         // otherwise tell it to drop its internal state
-        if (this.languageServiceEnabled && this.projectService.serverMode === LanguageServiceMode.Semantic && !this.isOrphan()) {
+        if (this.useTypingsFromGlobalCache()) {
             // 1. no changes in structure, no changes in unresolved imports - do nothing
             // 2. no changes in structure, unresolved imports were changed - collect unresolved imports for all files
             // (can reuse cached imports for files that were not changed)
@@ -1460,6 +1467,7 @@ export abstract class Project implements LanguageServiceHost, ModuleResolutionHo
         else {
             this.lastCachedUnresolvedImportsList = undefined;
         }
+        this.projectService.verifyUnresovedImports(this);
 
         const isFirstProgramLoad = this.projectProgramVersion === 0 && hasNewProgram;
         if (hasNewProgram) {
@@ -2361,7 +2369,8 @@ export abstract class Project implements LanguageServiceHost, ModuleResolutionHo
     }
 }
 
-function getUnresolvedImports(
+/** @internal */
+export function getUnresolvedImports(
     program: Program,
     cachedUnresolvedImportsPerFile: Map<Path, readonly string[]>,
     writeLog: (s: string) => void,