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Troubleshooting web apps migration issues

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This article describes some common issues and specific errors you might encounter when trying to migrate web apps using Azure Migrate.

Web Apps migration issues

This table lists the steps for fixing the following migration issues:

Error code Error message Troubleshooting steps
AccessDenied Access denied. Check error details. This may be due to a change since last web app discovery. Confirm that the web app discovery is still successful and/or troubleshoot web app discovery access issues first.
AddConflict The role assignment already exists. This may be due to AKS 1.23+ version. If you're using AKS 1.23+, edit the script as mentioned in Build container image before building the docker image.
AppContentAlreadyExists Application content appContent.zip already present on storage before content copy. Retry the migration using a new storage account. Contact support if this occurs persistently.
AppZipUploadFailed Error uploading application content to storage account. Retry if it's a transient issue and confirm connectivity between the appliance and the Azure storage account specified for the migration.
CopyAppContentToApplianceFailure Error occurred copying content from IIS web server to appliance. Check error details for more information. Confirm connectivity between appliance and web server such as by looking for recently successful web app discovery.
IISWebAppExceededMaxContentSize Content size exceeded max content size (2 GB) for migration using this tool. The deployment method used only supports content up to 2 GB in size. If uncompressed content is larger than 2 GB, migration won't be attempted with this error. This should be flagged in the web app assessment and may indicate file content size changes since the last web app discovery was completed.
IISWebAppFailureCompressingSiteContent Exception occurred compressing site content. Check error details for more information. This could be related to physical file permissions, including, if access has been blocked for the Administrator account used for the web app discovery and migration of the site content.
IISWebAppMigrationError Error occurred during app content copy operation. Check the error message for additional details.
IISWebAppNotFoundOnServer Web application matching site name not found on web server. This may be due to changes on the web server since the last web app discovery was completed, such as site delete or rename operations. Confirm that web app discovery was completed recently and that the site still exists on the web server.
IISWebAppUNCContentDirectory Web app contains only UNC directory content. UNC directories are not currently supported for migration. Currently, migration isn't supported for content on UNC shares. This error will occur if all site content is on UNC shares, if there are non-UNC share content directories those will be migrated.
IISWebServerAccessFailedError Unable to access the IIS configuration. This can be caused by insufficient access to IIS configuration and management API locations. Web app migration uses the same identity and connection mechanism as web app discovery. Check if settings have changed since the last successful web app discovery and if that discovery is still successful for this web server.
IISWebServerIISNotFoundError IIS Management Console feature is not enabled. This error indicates that the IIS Management Console feature isn't enabled on the web server, and is likely a change to the web server since the last successful web app discovery was completed. Ensure that the Web Server (IIS) role including the IIS Management Console feature (part of Management Tools) is enabled and that web app discovery can discover web apps for the target web server.
IISWebServerInvalidSiteConfig Invalid IIS configuration encountered, the site has no root application defined. This indicates an invalid site configuration for one or more sites on the IIS server. Add a root "/" application for all web sites on the IIS server or remove the associated (non-functional) sites.
IISWebServerPowerShellError Error occurred during PowerShell operation. Check the error message for more details. Remote PowerShell is used to package the site content from the web server without requiring the installation of any products or machine changes on the web server.
IISWebServerPowerShellVersionLessThan4 PowerShell version on IIS web server was less than minimum required PowerShell version 4. Migration is only supported for IIS web servers with PowerShell V4 or later versions. Update the web server with PowerShell v4 to enable this migration.
IISWebServerUnableToConnect Unable to connect to the server. Check error details. This may be due to a change since last successful web app discovery. Confirm that web app discovery is still successful and/or troubleshoot web app discovery access issues first.
IISWebServerZeroWebAppsFound No web apps were found on the target IIS server. This may indicate that the web server was modified after the last web app discovery was completed. Confirm that web app discovery was recently completed and that web apps weren't removed from the web server.
NullResult PowerShell script returned no results. Remote PowerShell is used for packaging the site content from the web server without requiring install of any products or persistent files on the server. This error may indicate that the MaxMemoryPerShell value on the IIS server is too low, or has been changed since web app discovery was completed. Try increasing the MaxMemoryPerShell value on the IIS server using a command like: Set-Item WSMan:\localhost\Shell\MaxMemoryPerShellMB 4096
ResultFileContentJSONParseError Results in unexpected format. Contact support if you're seeing this error.
ScriptExecutionTimedOutOnVm Operation timed out. This error may indicate a change on the server since last web app discovery. Check if web app discovery is still running and successful.
StorageAuthenticationFailed Failed to authenticate with Azure Storage container. Check the error details for more information.
StorageBlobAlreadyExists App content blob already present before upload of app content. Retry the migration using a new storage account.
StorageGenericError Azure Storage related error. The Azure Resource Manager deployment step will complete only when the content (appContent.zip) or an error file (error.json) appear in the site’s storage container – if the NuGet is unable to upload the error.json file in error cases, the Azure Resource Manager deployment will continue until it times out, waiting for the content. This may indicate an issue with connectivity between the appliance and the specified storage account being used by migration.
UnableToConnectToPhysicalServer Connecting to the remote server failed. Check error details. This may be due to a change since last web app discovery. Check for web app discovery errors and troubleshoot web app discovery connection issues first.
UnableToConnectToServer Connecting to the remote server failed. Check error details. This may be due to a change since last web app discovery. Check for web app discovery errors and troubleshoot web app discovery connection issues first.

Next steps