Fallout New California Not Installing

[ShadowLancer5]

So unless i get a fix i wasted 3 hours of my very busy day on this useless piece of horse Heck. "A problem occured during the install: The root element od a w3c xml schema should be <schema> and its namespace should be 'https://www.w3.org/2001/XMLSchema'. The mod WAS NOT INSTALLED. I dont want to manually install it because it will take another 3 hours unless i can find where the hell the 3 hour install went.

[M48A5]

It would appear you have the game installed in the worst place possible, "Program Files". It should be moved to another place on your harddrive or you will continue to have modding problems.

[dubiousintent]

As of 08 May 2018, the Nexus has changed some site security to come into compliance with the new "European Union General Data Protection Regulation" (EU GDPR) rules. This breaks older versions of NMM and other tools using the older unsecured API. It is usually reported as being "blocked by the Windows firewall" or causing a "script" or "W3C XML Schema" error installing mods. You will need to update it from NMM on GitHub (or this Nexus NMM download page but it's older than the GitHub version). Check the version numbers between those sites and use the latest release. Please see this Nexus site news article for details.

Some people are finding that even after updating NMM to v0.65.4 they still get a "script exception" message when installing some mods (such as UIO and MCM). This seems to be resolved by this suggestion from user ElysianMod:
* Run NMM as an "Administrator privileges" account.
* Go to NMM "Settings".
* Enable "Add Shell Extensions for Supported File Types".
* Then restart NMM.
(Supposedly this fix is included in "unofficial" update v0.65.7 and later to NMM on GitHub.)

Regardless of the above, did you install Steam to it's default location? If so, please see the wiki "Installing Games on Windows Vista+" article for why the original default Steam behavior of installing games to the "C:\Program Files" folder tree was bad (they learned better, and don't do that any more); and why "disabling UAC and running as Administrator" is NOT sufficient, with instructions how to move it. This is the single most important thing you can do to fix and protect yourself against problems in the future. As much of a PITA as that is, it's never going to be any easier than now. System updates often cause issues with games installed to these folder trees. Please see the 'Restoring to "Vanilla"' section of the wiki "FNV General Mod Use Advice" article as well.

If you did move Steam out of the default location, then likely any access privilege problem is one of "File and Folder permissions" on the parent "root" folder under which you installed the games. If this is not set correctly to allow at least "System", "Administrators", and "Users" to have "Full Control" then you can't overwrite other files or make changes. You then need to enable the "Properties | Security | Advanced | Change Permissions" setting of the parent folder to enable the box: "Replace all child object permissions with inheritable permissions from this object", so those changes get applied to the existing files and sub-folders.

-Dubious-