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- Pay-as-you-go Price Adjustments for Standard S3 CVMs in the Silicon Valley Region
- Vulnerability repairing for Linux images
- Stopping supporting for Ubuntu 10.04 images
- Solution to Tomcat Start Failure on Ubuntu14.04
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- Querying the Repossession Status of a Spot Instance
- No Charges When Shut Down for Pay-as-You-Go Instances
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- Managing Login Password
- Managing SSH Keys
- Spread Placement Group
- Unblocking Port 25
- Tags
- Monitoring and Alarms
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- Best Practice
- Best Practices
- Choosing the CVM Model
- Setting up a Website
- Building an Environment
- Building a Website
- Building an Application
- Building a Visual GUI
- Data Backup
- Uploading Local Files to CVM
- Copying Local Files to CVMs
- Uploading Files from Windows to a Windows CVM via MSTSC
- Uploading Files from MacOS to Windows CVM Using MRD
- Uploading Files from Linux to Windows CVM using RDP
- Uploading files via WinSCP to a Linux CVM from Windows
- Uploading Files from Linux or MacOS to Linux CVM via SCP
- Uploading Files from Linux to a CVM Using FTP
- Uploading Files from Windows to a CVM Using FTP
- Other CVM Operations
- CVM Access to COS via a Private Network
- Best Practices for Boot Mode Legacy BIOS and UEFI
- Recovering Data on Linux CVMs
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- High-throughput Network Performance Test
- Using USB/IP to Share USB Devices in Linux
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- Using AVX-512 Instructions to Accelerate AI Applications on CVM
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- Calling Cloud APIs via Python to Share Custom Images in Batches
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- Initializing Data Disks
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- System Activation
- System Updates
- System Shutdown
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- Windows Recovery Mode
- Updating the Virtio ENI Driver
- Modifying SID
- Modifying VNC Resolution
- Ensuring Unique SIDs for CVMs Using Sysprep
- Use of the atop Monitoring Tools by Linux Instances
- Introduction to Linux Kernel Parameters
- Others
- Troubleshooting
- Instance-Related Failures
- CVM Login Failures
- Windows Instance Login Failures
- Windows Instance Login Failures
- An authentication error occurred when you tried to log in to a Windows instance remotely
- Failed to Reset the CVM Password or the CVM Password Is Invalid
- Connection to a Windows CVM through Remote Desktop was denied
- Requires network-level identity verification
- Problems occurred when you tried to log in to a Windows CVM remotely on Mac
- Failed to log in to a Windows CVM due to high CPU and memory usage
- Failed to connect to a remote computer through Remote Desktop
- Credentials Not Work
- Windows instance: no remote Desktop license server can provide license
- Remote Login Failure Due To Port Issues
- Linux Instance Login Failures
- Linux Instance Login Failures
- Unable to Log in to a Linux Instance via SSH Key
- Failing to log in to a Linux CVM due to high CPU and memory usage
- Remote Login Failure due to Port Issues
- VNC Login Error (Module is Unknown)
- VNC Login Error (Account Locked due to XXX Failed Logins)
- VNC Login Error (Login Failed with Correct Password)
- VNC or SSH Login Error (Permission Denied)
- Login Failure Due to /etc/fstab Configuration Errors
- sshd Configuration File Permissions
- Infinite Loop Call in /etc/profile
- Login Failure Due to Server Isolation
- Login Failure Due to High Bandwidth Occupation
- Remote Connect Failure Due to Security Group Settings
- Troubleshooting Linux Instance Issues via VNC and Rescue Mode
- Failed to shut down or restart a CVM
- Network Namespace Creation Failure
- Kernel and IO Issues
- Missing System bin or lib Soft Link
- Suspected Infection with Virus
- "no space left on device" Error During File Creation
- Linux CVM Memory Issues
- Network Related Failures
- Instance-Related Failures
- API Documentation
- History
- Introduction
- API Category
- Making API Requests
- Region APIs
- Instance APIs
- DescribeInstances
- DescribeInstanceFamilyConfigs
- DescribeZoneInstanceConfigInfos
- DescribeInstanceTypeConfigs
- DescribeInstancesOperationLimit
- DescribeInstanceVncUrl
- InquiryPriceRunInstances
- InquiryPriceResetInstance
- InquiryPriceResetInstancesType
- InquiryPriceResizeInstanceDisks
- RunInstances
- StartInstances
- RebootInstances
- StopInstances
- ResetInstance
- TerminateInstances
- ResetInstancesType
- ResizeInstanceDisks
- ResetInstancesPassword
- ModifyInstancesAttribute
- ModifyInstancesProject
- InquirePricePurchaseReservedInstancesOffering
- DescribeReservedInstancesConfigInfos
- DescribeInstancesStatus
- PurchaseReservedInstancesOffering
- Cloud Hosting Cluster APIs
- Placement Group APIs
- Image APIs
- Key APIs
- Security Group APIs
- Network APIs
- Instance Launch Template APIs
- Data Types
- Error Codes
- FAQs
- Related Agreement
- Glossary
- Tutorial
- Release Notes and Announcements
- Release Notes
- Public Image Release Notes
- Announcements
- Updating Some Image Pip Package Management Tools for CentOS 7
- CentOS 8 End of Maintenance
- Discontinuation of Support for SUSE Commercial Images
- Price Reduction in Selected Availability Zones
- OrcaTerm Proxy IP Addresses Updates
- Pay-as-you-go Price Adjustments for Standard S3 CVMs in the Silicon Valley Region
- Vulnerability repairing for Linux images
- Stopping supporting for Ubuntu 10.04 images
- Solution to Tomcat Start Failure on Ubuntu14.04
- Upgrading Virtio network card drive for Windows CVMs
- About Configuration of Security Group Port 53
- Windows Server 2003 System Images End of Support Announcement
- End of Support for Windows Server 2008 R2 Enterprise Edition SP1 64-bit System Images
- Product Introduction
- Purchase Guide
- Getting Started
- Operation Guide
- Operation Guide Overview
- Use Limits
- Convenience Features
- Instances
- Creating Instances
- Managing Instance Launch Template
- Batch Sequential Naming or Pattern String-Based Naming
- Logging In to Linux Instances
- Logging in to Windows instance
- Adjusting Configuration
- View Instance Details
- Renaming Instances
- Resetting Instance Password
- Managing Instance IPs
- Changing Instance Subnet
- Changing Security Group
- Conversion from Pay-As-You-Go to Monthly Subscription
- Searching for Instances
- Exporting Instance List
- Renewing Instances
- Starting Up Instances
- Shutting Down Instances
- Restarting Instances
- Reinstalling System
- Using Tencent Cloud Automation Tools to execute commands
- Terminating/Returning Instances
- Enabling Instance Termination Protection
- Instance Repossession or Recovering
- Spot Instances
- Querying the Repossession Status of a Spot Instance
- No Charges When Shut Down for Pay-as-You-Go Instances
- Managing Roles
- Enabling and Disabling Hyper-Threading
- Reserved Instances
- Images
- Migrating Servers
- Maintenance Tasks
- Cloud Disks
- Networking
- Security
- Security Groups
- Protection of Sensitive Operations
- Managing Login Password
- Managing SSH Keys
- Spread Placement Group
- Unblocking Port 25
- Tags
- Monitoring and Alarms
- Sample Console Configuration
- Best Practice
- Best Practices
- Choosing the CVM Model
- Setting up a Website
- Building an Environment
- Building a Website
- Building an Application
- Building a Visual GUI
- Data Backup
- Uploading Local Files to CVM
- Copying Local Files to CVMs
- Uploading Files from Windows to a Windows CVM via MSTSC
- Uploading Files from MacOS to Windows CVM Using MRD
- Uploading Files from Linux to Windows CVM using RDP
- Uploading files via WinSCP to a Linux CVM from Windows
- Uploading Files from Linux or MacOS to Linux CVM via SCP
- Uploading Files from Linux to a CVM Using FTP
- Uploading Files from Windows to a CVM Using FTP
- Other CVM Operations
- CVM Access to COS via a Private Network
- Best Practices for Boot Mode Legacy BIOS and UEFI
- Recovering Data on Linux CVMs
- Managing Disk Space on Windows CVMs
- Changing Kernel of a Linux Instance Manually
- Setting Up Windows-based AD Domain on a CVM
- Network Performance Test
- High-throughput Network Performance Test
- Using USB/IP to Share USB Devices in Linux
- Using RemoteFx to Redirect USB Devices in Windows
- Using AVX-512 Instructions to Accelerate AI Applications on CVM
- Building Tencent SGX Confidential Computing Environment
- Configuring Persistent Memory in M6p Instances
- Calling Cloud APIs via Python to Share Custom Images in Batches
- Operations Guide
- Initializing Data Disks
- Environment Configurations
- Installing Software
- User Data
- Work with Operating Systems
- System Activation
- System Updates
- System Shutdown
- Configuring High-performance Power Management
- Windows Recovery Mode
- Updating the Virtio ENI Driver
- Modifying SID
- Modifying VNC Resolution
- Ensuring Unique SIDs for CVMs Using Sysprep
- Use of the atop Monitoring Tools by Linux Instances
- Introduction to Linux Kernel Parameters
- Others
- Troubleshooting
- Instance-Related Failures
- CVM Login Failures
- Windows Instance Login Failures
- Windows Instance Login Failures
- An authentication error occurred when you tried to log in to a Windows instance remotely
- Failed to Reset the CVM Password or the CVM Password Is Invalid
- Connection to a Windows CVM through Remote Desktop was denied
- Requires network-level identity verification
- Problems occurred when you tried to log in to a Windows CVM remotely on Mac
- Failed to log in to a Windows CVM due to high CPU and memory usage
- Failed to connect to a remote computer through Remote Desktop
- Credentials Not Work
- Windows instance: no remote Desktop license server can provide license
- Remote Login Failure Due To Port Issues
- Linux Instance Login Failures
- Linux Instance Login Failures
- Unable to Log in to a Linux Instance via SSH Key
- Failing to log in to a Linux CVM due to high CPU and memory usage
- Remote Login Failure due to Port Issues
- VNC Login Error (Module is Unknown)
- VNC Login Error (Account Locked due to XXX Failed Logins)
- VNC Login Error (Login Failed with Correct Password)
- VNC or SSH Login Error (Permission Denied)
- Login Failure Due to /etc/fstab Configuration Errors
- sshd Configuration File Permissions
- Infinite Loop Call in /etc/profile
- Login Failure Due to Server Isolation
- Login Failure Due to High Bandwidth Occupation
- Remote Connect Failure Due to Security Group Settings
- Troubleshooting Linux Instance Issues via VNC and Rescue Mode
- Failed to shut down or restart a CVM
- Network Namespace Creation Failure
- Kernel and IO Issues
- Missing System bin or lib Soft Link
- Suspected Infection with Virus
- "no space left on device" Error During File Creation
- Linux CVM Memory Issues
- Network Related Failures
- Instance-Related Failures
- API Documentation
- History
- Introduction
- API Category
- Making API Requests
- Region APIs
- Instance APIs
- DescribeInstances
- DescribeInstanceFamilyConfigs
- DescribeZoneInstanceConfigInfos
- DescribeInstanceTypeConfigs
- DescribeInstancesOperationLimit
- DescribeInstanceVncUrl
- InquiryPriceRunInstances
- InquiryPriceResetInstance
- InquiryPriceResetInstancesType
- InquiryPriceResizeInstanceDisks
- RunInstances
- StartInstances
- RebootInstances
- StopInstances
- ResetInstance
- TerminateInstances
- ResetInstancesType
- ResizeInstanceDisks
- ResetInstancesPassword
- ModifyInstancesAttribute
- ModifyInstancesProject
- InquirePricePurchaseReservedInstancesOffering
- DescribeReservedInstancesConfigInfos
- DescribeInstancesStatus
- PurchaseReservedInstancesOffering
- Cloud Hosting Cluster APIs
- Placement Group APIs
- Image APIs
- Key APIs
- Security Group APIs
- Network APIs
- Instance Launch Template APIs
- Data Types
- Error Codes
- FAQs
- Related Agreement
- Glossary
This document describes possible causes of Linux instance login failures and troubleshooting methods, helping you detect, locate and resolve problems.
Troubleshooting the Issue
Using the Diagnosis Tool
Tencent Cloud provides a diagnosis tool to help you determine whether the problem is due to common bandwidth, firewall, or security group configurations issues. More than 70% of the problems can be located by this tool. You can locate problems that result in login failures based on the detected causes.
1. Click Self-diagnose to open the self-diagnosis tool.
2. Select the target CVM instance as prompted and click Start Detection.
Using TAT to send commands
You can use TAT to send commands to an instance for troubleshooting and problem locating. The directions are as follows:
1. Log in to the CVM console and click the target instance ID in the instance list.
2. On the instance details page, select the Run Commands tab and click Execute command.
3. In the Execute command pop-up window, select a command as needed. Click Execute command and view the result.
For example, enter
df -TH and click Execute command to view the result of an instance without logging in to it.
For more information, see TencentCloud Automation Tools.Note:
If you cannot troubleshoot with the diagnosis tool, we recommend you log in to the CVM instance via VNC and follow the instructions.
Possible Cause
Common login failure reasons:
Troubleshooting
Logging in via VNC
If you cannot log in to the Linux instance by using Orcaterm or remote login software, you can try log in with VNC for troubleshooting.
1. Log in to the CVM console.
2. On the Instances page, select the target instance and click Log in.
3. In the Standard Login | Linux Instance window that pops up, select Login via VNC.
Note:
If you forgot the password for the instance, you can reset it in the console. For more information, see Resetting Instance Password.
4. Enter the username and password to login.
Login failure due to SSH issue
Problem: During login to a Linux instance using SSH, a message appears indicating that the connection is unavailable or failed.
Steps: See Unable to Use the SSH Method to Log in to a Linux Instance to perform troubleshooting.
Login failure due to password issue
Problem: The login attempt failed because you forgot the password, entered an incorrect password, or failed to reset your password.
Solution: Reset the password for this instance in the CVM console and restart the instance.
Procedure: See Resetting Instance Password for the detailed procedure.
High bandwidth utilization
Problem: The self-diagnosis tool shows that bandwidth utilization is too high.
Procedure:
1. Log in to the instance by using VNC login.
2. Check the bandwidth utilization of the instance and perform troubleshooting accordingly. For details, see Login Failure Due to High Bandwidth Occupation.
High instance load
Problem: The self-diagnosis tool or Tencent Cloud Observability Platform shows that server CPU workload is too high, and the system is unable to perform remote connection or access is slow.
Possible cause: Viruses, trojans, third-party antivirus software, application exceptions, driver exceptions, and automatic updates of software on the backend may lead to high CPU utilization, causing CVM login failures or slow access.
Procedure:
1. Log in to the instance by using VNC login.
2. In Task manager, find the process with a high load. For more information, see Failing to log in to a Linux CVM due to high CPU and memory usage.
Improper security group rules
Problems: The self-diagnosis tool shows that the security group rule configuration is improper, leading to login failures.
Procedure: Troubleshoot with the security group (port) verification tool.
Other Solutions
If you still cannot connect to the Linux instance, save your self-diagnosis results and submit a ticket for assistance.
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