Resilience to maintenance, migrations and retirements
Keep integrations running through Salesforce maintenance and change: skip callouts in read-only mode, recover Pub/Sub API clients after releases and org migrations, rebuild local external client apps after sandbox refreshes, plan for retiring APIs and features, and use circuit breakers, My Domain URLs, mTLS and Trust notifications.
Given a use case, identify the factors needed to build resilience in an integration solution for system updates.
~7 min read · 10 practice questions ·
What the exam expects
- Keep Apex integrations consistent during read-only maintenance by checking
System.getApplicationReadWriteMode(). - Recover Pub/Sub API clients after major releases and org migrations: new token, error-specific backoff, deduplication on event
id, and a fallback when retained events reset. - Plan for environment and platform change: local external client apps after sandbox refresh, SOAP
login()and API version retirements, legacy named credentials and other retiring features. - Isolate external outages with a circuit breaker and queued requests, and remove brittle endpoints and network rules (instance URLs, narrow IP allowlists).
Key terms: read-only mode (maintenance state where reads work and writes fail); org migration (moving an org to a new instance); retention window (72 hours of stored events); API Total Usage (Event Monitoring event type that shows API versions in use); circuit breaker (stops calling a failing system until probes show recovery).
Key facts
- Detail
- Execute; Salesforce writes are blocked
- Detail
INSERT_UPDATE_DELETE_NOT_ALLOWED_DURING_MAINTENANCE
org.migrated retry spacing- Detail
- At least 30 minutes apart
- Detail
- Event
id, notreplay_id
- Detail
- Not copied; only packaged apps are
login()- Detail
- API 64.0 and earlier; full retirement Summer '27
- Detail
- 410 GONE; versions 21.0-30.0 retired Summer '25
- Detail
- Support at least 3 years; notice at least 1 year
- Detail
- Not offered
Sources for this section (9)
- Callout Limits and Limitationsdeveloper.salesforce.com (opens in a new tab)
- Salesforce Read-Only Mode Overviewhelp.salesforce.com (opens in a new tab)
- Handle Errorsdeveloper.salesforce.com (opens in a new tab)
- Event Message Durabilitydeveloper.salesforce.com (opens in a new tab)
- External Client Appshelp.salesforce.com (opens in a new tab)
- login()developer.salesforce.com (opens in a new tab)
- Integration Patternsarchitect.salesforce.com (opens in a new tab)
- API End-of-Life Policydeveloper.salesforce.com (opens in a new tab)
- IP Addresses and Domains to Allowhelp.salesforce.com (opens in a new tab)
- Why should Apex check `getApplicationReadWriteMode()` before a callout?
- When should a Pub/Sub API client fetch a new token instead of backing off?
- What breaks after a sandbox refresh if the integration used a local external client app?
- How do you find integrations still calling old API versions?
The questions are free to read. Answers with their sources and self-grading are included with the pack.
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