diff --git a/models/db/index.go b/models/db/index.go
index 673c382b27fcf..1a6359c6ea453 100644
--- a/models/db/index.go
+++ b/models/db/index.go
@@ -47,6 +47,36 @@ func UpsertResourceIndex(ctx context.Context, tableName string, groupID int64) (
 	return err
 }
 
+// UpsertDecrResourceIndex the function will not return until it acquires the lock or receives an error.
+func UpsertDecrResourceIndex(ctx context.Context, tableName string, groupID, prevIdx int64) (err error) {
+	// An atomic UPSERT operation (INSERT/UPDATE) is the only operation
+	// that ensures that the key is actually locked.
+	// It will try to decrease the max_index, however if max_index is already higher,
+	// then don't try to decrease the index value.
+	switch {
+	case setting.Database.UseSQLite3 || setting.Database.UsePostgreSQL:
+		_, err = Exec(ctx, fmt.Sprintf("INSERT INTO %s (group_id, max_index) "+
+			"VALUES (?,1) ON CONFLICT (group_id) DO UPDATE SET max_index = CASE WHEN %s.max_index = %d THEN %s.max_index-1 ELSE %s.max_index END",
+			tableName, tableName, prevIdx, tableName, tableName), groupID)
+	case setting.Database.UseMySQL:
+		_, err = Exec(ctx, fmt.Sprintf("INSERT INTO %s (group_id, max_index) "+
+			"VALUES (?,1) ON DUPLICATE KEY UPDATE max_index = CASE WHEN max_index = %d THEN max_index-1 ELSE max_index END", tableName, prevIdx),
+			groupID)
+	case setting.Database.UseMSSQL:
+		// https://weblogs.sqlteam.com/dang/2009/01/31/upsert-race-condition-with-merge/
+		_, err = Exec(ctx, fmt.Sprintf("MERGE %s WITH (HOLDLOCK) as target "+
+			"USING (SELECT ? AS group_id) AS src "+
+			"ON src.group_id = target.group_id "+
+			"WHEN MATCHED THEN UPDATE SET target.max_index = CASE WHEN target.max_index = %d THEN target.max_index-1 ELSE target.max_index END"+
+			"WHEN NOT MATCHED THEN INSERT (group_id, max_index) "+
+			"VALUES (src.group_id, 1);", tableName, prevIdx),
+			groupID)
+	default:
+		return fmt.Errorf("database type not supported")
+	}
+	return err
+}
+
 var (
 	// ErrResouceOutdated represents an error when request resource outdated
 	ErrResouceOutdated = errors.New("resource outdated")
diff --git a/models/issues/issue.go b/models/issues/issue.go
index 49bc229c6bd03..c8c46de255f02 100644
--- a/models/issues/issue.go
+++ b/models/issues/issue.go
@@ -1077,12 +1077,27 @@ func NewIssue(repo *repo_model.Repository, issue *Issue, labelIDs []int64, uuids
 	}
 	defer committer.Close()
 
+	// onFail will try to gracefully revert the update in the resource index.
+	onFail := func() error {
+		// Close commiter.
+		committer.Close()
+		// Try to revert the increase in resource index.
+		if err := db.UpsertDecrResourceIndex(db.DefaultContext, "issue_index", repo.ID, idx); err != nil {
+			return fmt.Errorf("UpsertDecrResourceIndex: %v", err)
+		}
+		return nil
+	}
+
 	if err = NewIssueWithIndex(ctx, issue.Poster, NewIssueOptions{
 		Repo:        repo,
 		Issue:       issue,
 		LabelIDs:    labelIDs,
 		Attachments: uuids,
 	}); err != nil {
+		if err := onFail(); err != nil {
+			return fmt.Errorf("couldn't gracefully handle error: %v", err)
+		}
+
 		if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) || IsErrNewIssueInsert(err) {
 			return err
 		}
@@ -1090,6 +1105,10 @@ func NewIssue(repo *repo_model.Repository, issue *Issue, labelIDs []int64, uuids
 	}
 
 	if err = committer.Commit(); err != nil {
+		if err := onFail(); err != nil {
+			return fmt.Errorf("couldn't gracefully handle error: %v", err)
+		}
+
 		return fmt.Errorf("Commit: %v", err)
 	}
 
diff --git a/models/issues/pull.go b/models/issues/pull.go
index f96b03445e91f..392577b6a4bff 100644
--- a/models/issues/pull.go
+++ b/models/issues/pull.go
@@ -504,6 +504,17 @@ func NewPullRequest(outerCtx context.Context, repo *repo_model.Repository, issue
 	defer committer.Close()
 	ctx.WithContext(outerCtx)
 
+	// onFail will try to gracefully revert the update in the resource index.
+	onFail := func() error {
+		// Close commiter.
+		committer.Close()
+		// Try to revert the increase in resource index.
+		if err := db.UpsertDecrResourceIndex(outerCtx, "issue_index", repo.ID, idx); err != nil {
+			return fmt.Errorf("UpsertDecrResourceIndex: %v", err)
+		}
+		return nil
+	}
+
 	if err = NewIssueWithIndex(ctx, issue.Poster, NewIssueOptions{
 		Repo:        repo,
 		Issue:       issue,
@@ -511,6 +522,9 @@ func NewPullRequest(outerCtx context.Context, repo *repo_model.Repository, issue
 		Attachments: uuids,
 		IsPull:      true,
 	}); err != nil {
+		if err := onFail(); err != nil {
+			return fmt.Errorf("couldn't gracefully handle error: %v", err)
+		}
 		if repo_model.IsErrUserDoesNotHaveAccessToRepo(err) || IsErrNewIssueInsert(err) {
 			return err
 		}
@@ -521,10 +535,18 @@ func NewPullRequest(outerCtx context.Context, repo *repo_model.Repository, issue
 	pr.BaseRepo = repo
 	pr.IssueID = issue.ID
 	if err = db.Insert(ctx, pr); err != nil {
+		if err := onFail(); err != nil {
+			return fmt.Errorf("couldn't gracefully handle error: %v", err)
+		}
+
 		return fmt.Errorf("insert pull repo: %v", err)
 	}
 
 	if err = committer.Commit(); err != nil {
+		if err := onFail(); err != nil {
+			return fmt.Errorf("couldn't gracefully handle error: %v", err)
+		}
+
 		return fmt.Errorf("Commit: %v", err)
 	}