diff --git a/servers/fdr/src/controllers/docs/v2/getDocsWriteV2Service.ts b/servers/fdr/src/controllers/docs/v2/getDocsWriteV2Service.ts
index 6daa069759..6cf25999c3 100644
--- a/servers/fdr/src/controllers/docs/v2/getDocsWriteV2Service.ts
+++ b/servers/fdr/src/controllers/docs/v2/getDocsWriteV2Service.ts
@@ -55,12 +55,16 @@ export function getDocsWriteV2Service(app: FdrApplication): DocsV2WriteService {
             const customUrls = parseCustomDomainUrls({ customUrls: req.body.customDomains });
 
             // ensure that the domains are not already registered by another org
-            const hasOwnership = await app.dao.docsV2().checkDomainsDontBelongToAnotherOrg(
-                [fernUrl, ...customUrls].map((url) => url.getFullUrl()),
-                req.body.orgId,
-            );
+            const { allDomainsOwned: hasOwnership, unownedDomains } = await app.dao
+                .docsV2()
+                .checkDomainsDontBelongToAnotherOrg(
+                    [fernUrl, ...customUrls].map((url) => url.getFullUrl()),
+                    req.body.orgId,
+                );
             if (!hasOwnership) {
-                throw new DomainBelongsToAnotherOrgError("Domain belongs to another org");
+                throw new DomainBelongsToAnotherOrgError(
+                    `The following domains belong to another organization: ${unownedDomains.join(", ")}`,
+                );
             }
 
             const docsRegistrationId = DocsV1Write.DocsRegistrationId(uuidv4());
diff --git a/servers/fdr/src/db/docs/DocsV2Dao.ts b/servers/fdr/src/db/docs/DocsV2Dao.ts
index 61ec735ab0..5e17891b5f 100644
--- a/servers/fdr/src/db/docs/DocsV2Dao.ts
+++ b/servers/fdr/src/db/docs/DocsV2Dao.ts
@@ -33,8 +33,13 @@ export interface LoadDocsConfigResponse {
     referencedApis: string[];
 }
 
+export interface CheckDomainOwnershipResponse {
+    allDomainsOwned: boolean;
+    unownedDomains: string[];
+}
+
 export interface DocsV2Dao {
-    checkDomainsDontBelongToAnotherOrg(domains: string[], orgId: string): Promise<boolean>;
+    checkDomainsDontBelongToAnotherOrg(domains: string[], orgId: string): Promise<CheckDomainOwnershipResponse>;
 
     loadDocsForURL(url: URL): Promise<LoadDocsDefinitionByUrlResponse | undefined>;
 
@@ -88,10 +93,14 @@ export class DocsV2DaoImpl implements DocsV2Dao {
         });
     }
 
-    public async checkDomainsDontBelongToAnotherOrg(domains: string[], orgId: string): Promise<boolean> {
+    public async checkDomainsDontBelongToAnotherOrg(
+        domains: string[],
+        orgId: string,
+    ): Promise<CheckDomainOwnershipResponse> {
         const matchedDomains = await this.prisma.docsV2.findMany({
             select: {
                 orgID: true,
+                domain: true,
             },
             where: {
                 domain: {
@@ -101,7 +110,14 @@ export class DocsV2DaoImpl implements DocsV2Dao {
             distinct: ["orgID", "domain"],
         });
 
-        return matchedDomains.every((matchedDomain) => matchedDomain.orgID === orgId);
+        const allDomainsOwned = matchedDomains.every((matchedDomain) => matchedDomain.orgID === orgId);
+        const unownedDomains = matchedDomains
+            .filter((matchedDomain) => matchedDomain.orgID !== orgId)
+            .map((matchedDomain) => matchedDomain.domain);
+        return {
+            allDomainsOwned,
+            unownedDomains,
+        };
     }
 
     public async loadDocsForURL(url: URL): Promise<WithoutQuestionMarks<LoadDocsDefinitionByUrlResponse> | undefined> {