Sometimes when you try to download a new SCCM update in Updates and Servicing node it may stuck indefinitely in “Downloading” state. When you check dmpdownloader.log you may see the following error:
ERROR: Failed to download redist for 0f11caa4-7f7f-454b-96d6-75f427d015ce with command /RedistUrl http://go.microsoft.com/fwlink/?LinkID=857597 /LnManifestUrl http://go.microsoft.com/fwlink/?LinkID=854716 /RedistVersion 201706 /ProxyUri http://companyproxy:81/ /ProxyUserName CONTOSO\SCCM_Admin /ProxyUserPassword 3082018F06092A864886F70D010703A08201803082017C020102318201303082012C0201028014A8 /NoUI “\\SCCM01.contoso.com\EasySetupPayload\0f11caa4-7f7f-454b-96d6-75f427d015ce\redist”
This error is not very descriptive however it indicates the problem with SCCM prerequisites download. Additionally when you go to Program Files\Microsoft Configuration Manager\EasySetupPayload folder you would see both 0f11caa4-7f7f-454b-96d6-75f427d015ce folder and 0f11caa4-7f7f-454b-96d6-75f427d015ce.cab file. The code may be different depending on the upgrade.
The root cause of this issue is your firewall or proxy or something else which blocks specific files from downloading assuming this is a security threat. The workaround is:
Go to 0f11caa4-7f7f-454b-96d6-75f427d015ce\SMSSETUP\BIN\X64 ad copy SetupDL.exe to the computer with has unprotected access to Internet. Run SetupDL.exe <Destination folder>. Once download is completed, copy all files and folders structure to 0f11caa4-7f7f-454b-96d6-75f427d015ce\redist folder and run updates check or (better) restart SMS_EXECUTIVE service. SCCM will detect your files and 0f11caa4-7f7f-454b-96d6-75f427d015ce.cab file should disappear.
If you do not have “clean Internet” running SetupDL.exe output would at least give you an indication what file cannot be downloaded. In that case download ConfigMgr.Manifest.cab and ConfigMgr.LN.Manifest.cab using links from the error message above (/RedistUrl http://go.microsoft.com/fwlink/?LinkID=857597 and /LnManifestUrl http://go.microsoft.com/fwlink/?LinkID=854716), unpack both cab files, open .xml manifest files in Notepad and download every missing prerequisite file individually using HTTP links from the manifest files.