- The error message "SERVER_UNAVAILABLE: Too many requests waiting for connections" indicates the app server processing the current request on the given instance was unable to obtain a database connection at the given time.
- While the service is continuously dimensioned to minimize the frequency of occurrence of this error message and ensure high availability at all times, sudden load spikes on a given instance might cause this error message to be returned to integrations if the requests being currently processed are database intensive, and connections do not become available in a given amount of time.
- Salesforce Site Reliability closely monitors service availability on a continuous basis and will take any necessary actions to ensure the frequency of these errors is as low as possible.
- Trust is our #1 priority and a posting will be made at trust.salesforce.com if a confirmed performance degradation takes place on a given instance at a given time. However there might be occasions when no posting will be made if the database was under intensive utilization for a very narrow time window only.
- It is recommended to raise a case with Support if the error is persistent or is experienced with high frequency on a given instance and no posting has been found in Trust. Support will ensure the issue is investigated with the maximum diligence.
- At the same time, customers are suggested to investigate how to implement retry logic that can handle these errors should they occur as to minimize any potential impact. The retry logic should use the binary exponential backoff algorithm, e.g. retry after 1 second; if it fails, retry after 2 seconds; if it fails, retry after 4 seconds, etc.