My BEX Server is installed on Win2012R2 and is using file share without ddup as storage device. BEX server and file server are located in different networks with GRE tunnel between them (50 Mbps link).
BEX was installed in 2017 and everything worked OK for almost 3 years. But recently (2-3 months ago) after some Windows updates (I suppose that all the problems were introduced by updates, cause nothing was changed in server or network configuration) all full backups stopped working.
All full backup jobs to remote server fails with error E00084ED (I see corresponding error in Event Viewer: An error occurred while processing a B2D command. Drive: Write() WriteFile failed 0/1024 @262659 (\\172.30.30.15\Backup\B2D027116.bkf). Error=64) if they include drive C backup. Failure always happen @ about 2-3 GB of beginning. If backup job does not include drive C, it completes successfully. Also the same incremental backup jobs works fine. System state portion of backup also succeeded despite the fact that its size is about 12-13 GB. Backup jobs with ESX virtual machines also works fine (full and incremental). So only full backup jobs with drive C are broken.
If I run 2 jobs simultaneously (erroneous one and normal one), full backup with drive C fails with above error and full backup without drive C completes without any errors. And they both writes to the same file share, which means that there are no problems with the network or file share.
I've been digging on the Internet for 3 days, I read tons of solutions for E00084ED, but could not find sutable one. Please, help.