[59387] ALARM: "FrontEnd Alerts" in US East (Ohio)

[siddhirlpl]

Automated fix for Freshservice ticket 59387.
Confidence: 0.95
Reproduction: confirmed
Ticket: https://serviceone.freshservice.com/helpdesk/tickets/59387
OpsGenie alert: 4079a401-de85-488b-8887-2a7ed326fe28-1783313473969

Investigation summary

Investigation Summary for Application Error Alert

Alert Details:
• ID: 4079a401-de85-488b-8887-2a7ed326fe28-1783313473969
• Alias: US East (Ohio) - FrontEnd Alerts
• Status: open
• Created At: 2026-07-06T04:51:13.969Z
• Source: CloudWatch
• Priority: P3

1. Quick Identification Steps

Alert type: Application Error. The alarm is for QuotesApp frontend and the prefetched CloudWatch log evidence shows a frontend runtime exception.

What failed exactly:
• The frontend click handler failed with TypeError: r.toUpperCase is not a function.
• This occurred on route / in the browser-side bundle main.2faff39b.js.

Why it failed:
• The log evidence indicates the code attempted to call toUpperCase() on a value that was not a string.
• This is a frontend input/type handling bug, not an infrastructure or network issue.

2-minute pre-alert evidence window:
• Alert state change time: 2026-07-06T04:51:13.651+0000
• Relevant error timestamp: 2026-07-06T04:50:07.978000+00:00
• This falls within the 2-minute pre-alert window and directly supports the alarm trigger.

ELK Log Findings:
• Index searched: research-prod-rlcatalyst-app-logs
• Time range searched: last 6 minutes, then last 1 hour
• Result: no error-level logs found in either research-prod-rlcatalyst-app-logs or research-alias
• HTTP error count check: nginx-* showed 0 errors in the last 2 hours

Evidence from the prefetched application log:
• 2026-07-06T04:50:07.978000+00:00 — r.toUpperCase is not a function
• Stack trace points to onClick in the frontend bundle
• Route affected: /

Impact scope:
• Affects frontend interactions on the QuotesApp root page.
• Likely impacts users who trigger the specific click path that passes a non-string value into the handler.
• No evidence of broader backend, nginx, or platform-wide error spikes from the queried logs.

Root cause:
• Frontend type mismatch / unsafe assumption in client-side code.
• The handler is calling toUpperCase() on a non-string value, causing a runtime

Confirmed root cause

In createPost (src/App.js:46), localStorage.setItem called JSON.stringify(updatedPosts.toUpperCase()) on updatedPosts, which is an array. Arrays have no toUpperCase method, causing TypeError: r.toUpperCase is not a function when users click Create Post on route /.

Reproduction steps

• Started QuotesApp dev server at http://localhost:3000/ (route /)
• Rendered App with mocked /quotes/random response so quote and author load and Create Post is enabled
• Clicked the Create Post button (onClick -> createPost in src/App.js)
• Observed runtime failure when createPost calls updatedPosts.toUpperCase() on an array at src/App.js:46

Evidence

Jest click reproduction output: REPRO_EVIDENCE: Error: updatedPosts.toUpperCase is not a function (matches prod log: r.toUpperCase is not a function). Root cause line: localStorage.setItem('posts', JSON.stringify(updatedPosts.toUpperCase())); in src/App.js:46 where updatedPosts=[...posts, newPost] is an array.

Files changed

• src/App.js

Verification

• npm test — pass
• npm run build — pass

Fix summary

Removed the erroneous .toUpperCase() call on the posts array in createPost so posts are persisted with JSON.stringify(updatedPosts), matching the existing deletePost pattern. This prevents the runtime TypeError when clicking Create Post and correctly saves new posts to localStorage.

Remaining risks

• No unit tests in the repository cover createPost; regression relies on manual or external reproduction tests.