Azure App Service
Azure App Service is a service used to create and deploy scalable, mission-critical web apps.
The issue seems to be related to app service to db communication
Website down and shows db connection error.
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Thomas John
0
Reputation points
Website down and shows db connection error. error establishing connection to database.
Azure App Service
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(128, 8%, 22%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EA%3C/text%3E%3C/svg%3E)
Anonymous2025-04-08T23:11:59.4066667+00:00 Hi Thomas John,
Kindly help me with the details below so I can better assist you in resolving the issue.
- Which Azure services are being used to host your website and database?
- Have there been any recent changes to your app settings, database configuration, or connection strings?
- Is the database currently running, and are you able to connect to it directly?
- Is the connection string in your application correct and using valid credentials?
- Can you share the exact error message you're seeing related to the database connection?
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Thomas John 0 Reputation points
2025-04-08T23:22:54.6766667+00:00 1.Web(App service containers), db(mysql)
- No changes to the app/db side but recently there were too many intermittent health failures. Then aut recover in minutes time
- Db is currently restarted again due but restart failed
- nochanges to connection string
5.Error establishing a database connection
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2 answers
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Thomas John 0 Reputation points
2025-04-09T01:24:14.2366667+00:00 -
Anonymous
2025-04-09T17:16:11.6+00:00 Hi Thomas John,
Thanks for the update. The database connection error is likely due to the MySQL server being unresponsive from
high CPU usageor afailed restart—this is the root cause, while the App Service communication issue is just a symptom. Focus on restoring the database(scale or restore), then check connectivity from theApp Service.- Check database availability by connecting from another machine using
MySQL CLIorWorkbench, if it doesn't respond, the issue is with the database, so follow thescale-uporrestoresteps provided earlier. - Please Check App Service Logs by navigating to App Service → Diagnose and Solve Problems → Availability and Performance → Application Logs / HTTP Logs. Look for
connection errorsortimeoutsto see if the issue is not with the code. - Please check
networkingsettings if your App Service usesVNet Integration, make sure DNS resolution works and routes to the database subnet are correct. If the MySQL database uses aPrivateEndpoint, verify thatNSG rulesandPrivate DNS Zonesare properly configured. - Verify the connection string by checking if the database hostname resolves from the
App Service consoleusing Kudu → SSH → nslookup <db-host>.
- Check database availability by connecting from another machine using
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Anonymous
2025-04-10T16:52:34.9633333+00:00 Hi Thomas John,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
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Anonymous
2025-04-11T18:10:21.1033333+00:00 Hi Thomas John,
We haven’t heard from you on the last response and was just checking back to see if you have a resolution yet. In case if you have any resolution, please do share that same with the community as it can be helpful to others. Otherwise, will respond with more details and we will try to help.
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Thomas John 0 Reputation points
2025-04-08T23:32:43.4733333+00:00 Db restart hasbeen failed, stuck there for almost 45mins and still stuck with start. All those period the CPU from db is around 100%
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Anonymous
2025-04-09T00:34:59.7366667+00:00 Hi Thomas John,
It looks like your MySQL database is stuck while restarting due to
high CPUusage, likely caused by a resourcebottleneckor aninternalrecovery process. Since it's been stuck for a while, it may need manual intervention or a temporary scale-up to recover.- Temporarily
scaling upthe MySQL server's compute (vCores and memory) can help it recover if it's stuck restarting due to high CPU usage.
Open your MySQL server in the Azure Portal → Go to Compute + Storage → Increase vCores and memory → Save and wait for the scaling to complete.
- Don’t restart the MySQL server too often when it’s under
high load—it can slow down recovery. After scaling up, let it run and check if CPU and memory usage improve. - Download and review the
MySQL server logsto identify issues like corrupted tables, long-running queries, or permission errors causing the restart to fail.
az mysql server-logs list --name <server-name> --resource-group <resource-group> az mysql server-logs download --name <server-name> --resource-group <resource-group> --file-name <log-file>- Check
CPU, storage, and IOusage in Azure Portal under Monitoring → Metrics, and if they're high, scale up or clean up data to help MySQL start and run smoothly. - If the MySQL server remains unresponsive after scaling and log review,
restoreit from a recent Azure backup to a new instance for a quick recovery.
In the Azure Portal, go to your MySQL server → Select Restore and choose a timestamp before the issue began → Deploy it as a new server instance → Update your app's connection string to point to the new server.
https://learn.microsoft.com/en-us/azure/mysql/flexible-server/how-to-restore-server-portal
- Temporarily
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