PSA: Windows 10 V1803: Update KB4284848 brings SMBv1 fix

[German]Microsoft has kept its word and delivered the fix for the broken SMBv1 protocol in Windows 10 April Update (V1803) with update KB4284848 in June 2018.


What's the SMBv1 issue?

Microsoft had already announced since summer 2017 that support for the SMBv1 protocol in Windows 10 will expire. The abbreviation SMB stands for Server Message Block (former names are LAN Manager or NetBIOS protocol), a network protocol for file, print and other server services in computer networks. Version 1 (SMBv1) of the network protocol designed over 30 years ago, and especially the Microsoft implementation, is considered very error-prone and security-critical (see Microsoft plans to deactivate SMBv1 in  Windows 10 V1709 and StopUsingSMB1)..

In the meantime there are SMBv2 and SMBv3, so that the use of SMBv1 in Windows networks is no longer absolutely necessary. For example, Windows Vista is no longer dependent on SMBv1 because SMBv2 is used there.

In May 2018 Microsoft released the updates KB4103721 (05/08/2018) and KB4100403(05/23/2018) for Windows 10 V1803. However, after upgrading to Windows 10 V1803 or installing these updates, users of Windows 10 April Update seem to experience issues when using the SMBv1 protocol. I noticed postings in the Microsoft-Answers forums, where my hint to try to activate SMBv1 once did not brought success. I couldn't figure it out at first, until Microsoft has added the following paragraph in the 'Known issues' section of the two KB articles mentioned above.

Some users running Windows 10 version 1803 may receive an error "An invalid argument was supplied" when accessing files or running programs from a shared folder using the SMBv1 protocol.

I've addressed this issue within my blog post Microsoft plans a Windows 10 V1803 SMBv1 fix on June 2018.

Update KB4284848 brings the SMBv1 Fix

On June 26, 2018 Microsoft released the cumulative update KB4284848 for Windows 10 V1803 (see Windows 10 V1803: Update KB4284848 (June 26, 2018)). And within the list of fixes you will find the following note: 


Addresses an issue where some users may receive an error when accessing files or running programs from a shared folder using the SMBv1 protocol. The error is "An invalid argument was supplied".

Exactly the error described above is promised to be fixed. The question remains: Was someone affected by this bug and can it be determined that the problem has been fixed?

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