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The basic problem is that the installation files for SMB1 are not contained within the Server 2019 image that's deployed in Azure. However, you can specify a source for the installation files and continue the install. HOWEVER, if you have updated your Azure VM to the latest updates, you can no longer use the evaluation Server 2019 ISO File as a source.
- Install a fresh copy of Windows Server 2019 to a temporary server and join it to domain. Make sure the build number is 17763.737 or lower.
- Attach the Windows Server 2019 evaluation ISO to the server. Install the SMB1 feature and enter WIM:E:\sources\install.wim:4 as the source.
- Reboot the server once the feature is installed
- Install all the latest updates to the server and reboot
- Share the C:\windows\winsxs folder on the server. Give "everyone" read permission.
- Go to the server where you are unable to install SMB1. Do the installation but put the source as \servername\winsxs that you shared in step 5. The installation will complete.
Please refer to this link for more detailed steps- https://blog.baeke.info/2020/06/08/adding-smb1-protocol-support-to-windows-server-2019/
Note: There are links to non-Microsoft websites. The pages appear to be providing accurate, safe information. Watch out for ads on the sites that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the sites before you decide to download and install it.
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