---
id: 77a440d8-af1a-4e16-9ee4-c4e916014d6c
---

# High number of client-side request errors with HAProxy
---

This incident type refers to a high number of client-side request errors for a specific service, in this case HAProxy. This can be caused by various reasons such as client timeout, connection termination or read errors from the client. The incident is triggered when the error rate deviates from the predicted value and exceeds a certain threshold. This incident can affect the end-users' experience and requires immediate attention to prevent further issues.

### Parameters
```shell
# Environment Variables

export HAPROXY_CFG="PLACEHOLDER"

export HAPROXY_LOG="PLACEHOLDER"

export SERVER_IP="PLACEHOLDER"

export SERVER_NAME="PLACEHOLDER"

export SERVER_LOG="PLACEHOLDER"

export INTERFACE="PLACEHOLDER"

export MAX_CONNECTIONS="PLACEHOLDER"

```

## Debug

### Check HAProxy status
```shell
systemctl status haproxy
```

### Check the HAProxy configuration file for any syntax errors
```shell
haproxy -c -V -f ${HAPROXY_CFG}
```

### Check the current number of client-side request errors
```shell
tail -n 1000 ${HAPROXY_LOG} | grep "client-side request error"
```

### Check the network connectivity between the client and the server
```shell
ping ${SERVER_IP}
```

### Check the DNS resolution for the server
```shell
nslookup ${SERVER_NAME}
```

### Check the server logs for any errors or issues
```shell
tail -n 1000 ${SERVER_LOG} | grep "error"
```

### Check the server's firewall configuration to ensure it's not blocking traffic
```shell
iptables -L
```

### Check the server's resource utilization
```shell
top
```

### Security-related issues such as DDoS attacks or malicious traffic that cause anomalies in the error rate.
```shell
bash

#!/bin/bash

# Set variables

LOG_FILE="/var/log/haproxy.log"

ERROR_THRESHOLD=1000

ANOMALY_THRESHOLD=10

# Check for anomalies in error rate

anomalies=$(grep "haproxy.*frontend.*errors.*req_rate" $LOG_FILE | awk '{print $NF}' | awk -F'[,%]' '{print $1}')

max_anomaly=$(echo "$anomalies" | sort -nr | head -n 1)

if [ "$max_anomaly" -ge "$ANOMALY_THRESHOLD" ]; then

    echo "Anomalies detected in error rate. Maximum anomaly is $max_anomaly."

    # Check for DDoS attacks or malicious traffic

    errors=$(grep "haproxy.*frontend.*errors.*req_rate" $LOG_FILE | awk '{print $NF}' | awk -F'[,%]' '{if ($1 >= '$ERROR_THRESHOLD') print $0}')

    if [ -n "$errors" ]; then

        echo "Potential DDoS or malicious traffic detected:"

        echo "$errors"

    else

        echo "No DDoS or malicious traffic detected."

    fi

else

    echo "No anomalies detected in error rate."

fi


```

## Repair

### Updates the maximum connections .
```shell

#!/bin/bash

# Set the maximum connections

MAX_CONNECTIONS=${MAX_CONNECTIONS}

# Update the HAProxy configuration file

sudo sed -i "s/maxconn [0-9]*/maxconn $MAX_CONNECTIONS/" ${HAPROXY_CFG}

# Reload the HAProxy service

sudo systemctl reload haproxy.service
```


This incident type refers to a high number of client-side request errors for a specific service, in this case HAProxy. This can be caused by various reasons such as client timeout, connection termination or read errors from the client. The incident is triggered when the error rate deviates from the predicted value and exceeds a certain threshold. This incident can affect the end-users' experience and requires immediate attention to prevent further issues.


This incident type occurs when the number of 5xx errors on Traffic Server is higher than usual. This can indicate issues with server performance or connectivity problems. It requires investigation to identify the root cause and resolve the issue.


High 5xx Errors on Traffic Server

This incident type occurs when the number of 4xx errors on Traffic Server is at an anomalous level, higher than usual. It could be an indicator of an issue with the server or an increase in traffic that is causing errors. It requires investigation and resolution to ensure the server is functioning correctly and not impacting users.


High 4xx Errors on Traffic Server

This incident type occurs when the size of HTTP request headers or payload exceeds the limits set by Tomcat server. When this happens, the server may reject the request or return an error message, causing disruption to the normal functioning of the web application. This can be caused by a variety of factors, including large file uploads, excessive use of cookies or query parameters, or attacks that intentionally send oversized requests.


Tomcat HTTP Request Headers or Payload Size Exceeds Limits.

This incident type refers to an increase in the number of errors per second on a Tomcat server, which could indicate an issue with the server itself, the host, a deployed application, or an application servlet. This could include errors generated when the Tomcat server runs out of memory, can't find a requested file or servlet, or is unable to serve a JSP due to syntax errors in the servlet codebase. This incident type requires immediate attention to diagnose and address the underlying issue.


Increase of the errors/second rate for Tomcat server

This incident type refers to a situation where the number of 5xx errors on NGINX upstreams is higher than usual. It is an indication that there could be an issue with the NGINX server or the upstream application server. This type of incident requires immediate attention as it can impact the availability and performance of the application.


Higher than usual 5xx Errors for NGINX

```shell
# Environment Variables

export HAPROXY_CFG="PLACEHOLDER"

export HAPROXY_LOG="PLACEHOLDER"

export SERVER_IP="PLACEHOLDER"

export SERVER_NAME="PLACEHOLDER"

export SERVER_LOG="PLACEHOLDER"

export INTERFACE="PLACEHOLDER"

export MAX_CONNECTIONS="PLACEHOLDER"

```


### Check HAProxy status

```shell
systemctl status haproxy
```

### Check the HAProxy configuration file for any syntax errors

```shell
haproxy -c -V -f ${HAPROXY_CFG}
```

### Check the current number of client-side request errors

```shell
tail -n 1000 ${HAPROXY_LOG} | grep "client-side request error"
```

### Check the network connectivity between the client and the server

```shell
ping ${SERVER_IP}
```

### Check the DNS resolution for the server

```shell
nslookup ${SERVER_NAME}
```

### Check the server logs for any errors or issues

```shell
tail -n 1000 ${SERVER_LOG} | grep "error"
```

### Check the server's firewall configuration to ensure it's not blocking traffic

```shell
iptables -L
```

### Check the server's resource utilization

```shell
top
```

### Security-related issues such as DDoS attacks or malicious traffic that cause anomalies in the error rate.

```shell
bash

#!/bin/bash

# Set variables

LOG_FILE="/var/log/haproxy.log"

ERROR_THRESHOLD=1000

ANOMALY_THRESHOLD=10

# Check for anomalies in error rate

anomalies=$(grep "haproxy.*frontend.*errors.*req_rate" $LOG_FILE | awk '{print $NF}' | awk -F'[,%]' '{print $1}')

max_anomaly=$(echo "$anomalies" | sort -nr | head -n 1)

if [ "$max_anomaly" -ge "$ANOMALY_THRESHOLD" ]; then

    echo "Anomalies detected in error rate. Maximum anomaly is $max_anomaly."

    # Check for DDoS attacks or malicious traffic

    errors=$(grep "haproxy.*frontend.*errors.*req_rate" $LOG_FILE | awk '{print $NF}' | awk -F'[,%]' '{if ($1 >= '$ERROR_THRESHOLD') print $0}')

    if [ -n "$errors" ]; then

        echo "Potential DDoS or malicious traffic detected:"

        echo "$errors"

    else

        echo "No DDoS or malicious traffic detected."

    fi

else

    echo "No anomalies detected in error rate."

fi


```


### Updates the maximum connections .

```shell

#!/bin/bash

# Set the maximum connections

MAX_CONNECTIONS=${MAX_CONNECTIONS}

# Update the HAProxy configuration file

sudo sed -i "s/maxconn [0-9]*/maxconn $MAX_CONNECTIONS/" ${HAPROXY_CFG}

# Reload the HAProxy service

sudo systemctl reload haproxy.service
```


High number of client-side request errors with HAProxy

Overview

Parameters

Debug

Check HAProxy status

Check the HAProxy configuration file for any syntax errors

Check the current number of client-side request errors

Check the network connectivity between the client and the server

Check the DNS resolution for the server

Check the server logs for any errors or issues

Check the server's firewall configuration to ensure it's not blocking traffic

Check the server's resource utilization

Repair

Updates the maximum connections .

Learn more

Related Runbooks

High 5xx Errors on Traffic Server

High 4xx Errors on Traffic Server

Tomcat HTTP Request Headers or Payload Size Exceeds Limits.

Increase of the errors/second rate for Tomcat server

Support