[Sophos Advisory] SafeGuard File Encryption: BSOD - UNEXPECTED_KERNEL_MODE_TRAP (7f) after upgrade or installation on Windows 10 version 1803

Question

Hey Community, 
 Sophos is investigating a few reported occasions of a BSOD - UNEXPECTED_KERNEL_MODE_TRAP (7f) on computers running one of the SafeGuard File Encryption modules e.g. File Encryption, Synchronized Encryption, Data Exchange, Cloud Storage. The BSOD occurs after the update to the latest Windows 10 feature release version 1803 (build 17134). 
 The issue only affects a small subset of computers and is not yet reproducible internally. On affected systems it apparently only occurs, when logging on with a domain account. 
 Based on a first analysis, the reason is a stack overflow caused by a kernel function. The involvement of SafeGuard is yet unclear. 
 Please follow this Advisory KBA for more information and updates as they become available. 
 Regards,

FloSupport · Answer

Update (May 18th 2018): 
 The root cause has been found and a patch is being developed. According to current planning, a first version will be available by 25th of May. 
 A workaround has been provided in the KBA for experienced users in the meantime.