The Joomla core autoloader requires that developers use case sensitive names matching our class declarations (and inherently the filesystem structure based on its rules) if a class hasn't been loaded into memory. We don't have a Jstring class in core, but there is JString, and that one will correctly autoload. So scan your code and see if there are any class declarations that don't use the correct casing and fix those (or report the issue to the extension developer in question).

I am sorry but I am not very literate when it comes to the coding site of the files in my installation. Can you specify where I would look for this?

Just to be sure you are saying this is actually a extension causing this and not anything to do with the Joomla core files?

If it is an extension I am sorry for posting here. I assumed it has something to do with the core files when they were updated to 3.7.x because all pages load fine on previous builds before 3.7.x.

Just to be sure you are saying this is actually a extension causing this and not anything to do with the Joomla core files?

The exact error message would help here. But changes are very high that it is an extension (eg a content or system plugin) causing this.

I'm closing this issue. If you can reproduce the issue on a clean Joomla installation it can be reopened,

I have disabled all extensions but the core joomla ones and the error still persists. The exact error is 0 - Class 'Jstring' not found.

We would need exakt steps to reproduce this on a clean Joomla install.
Disabling extensions isn't th same thing.

Set to "open" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/16096

reopened as Discussion going on.

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/16096.}

I am doing a brand new clean installation now and will report back ASAP. Thanks for re-opening!

I have narrowed it down to 1 specific module that does not get along with Joomla 3.7 or 3.7.1 - JoomlaXTC Deluxe News Pro , I disabled that module & all pages load right up. some of the errors I am getting are as follows:

A parse error has occurred while processing the following JSON data:

// </script> <style>#scrollToTop{cursor:pointer;font-size:0.9em;position:fixed;text-align:center;z-index:9999;-webkit-transition:background-color 0.2s ease-in-out;-moz-transition:background-color 0.2s ease-in-out;-ms-transition:background-color 0.2s ease-in-out;-o-transition:background-color 0.2s ease-in-out;transition:background-color 0.2s ease-in-out;background:#1500ff;color:#518f3e;border-radius:3px;padding-left:12px;padding-right:12px;padding-top:12px;padding-bottom:12px;right:20px;bottom:20px;}#scrollToTop:hover{background:#ffffff;color:#ffffff;}#scrollToTop>img{display:block;margin:0 auto;}#gototop{border:1px solid #0;margin:5px;padding:5px;background-color:#ff0;color:#0;}#gototop:hover{background-color:#0;color:#ff0;}@media (max-width: 480px) {.view-login .container{margin-top:-170px;}.btn{font-size:13px;padding:4px 10px 4px;}}</style> <script type="application/json" class="joomla-script-options new">{"system.keepalive":{"interval":3600000,"uri":"\/administrator\/index.php"}}</script> <script src="/media/jui/js/jquery.min.js?2e60e68fb95354eb9c457ede7e3eb866"></script> <script src="/media/jui/js/jquery-noconflict.js?2e60e68fb95354eb9c457ede7e3eb866"></script> <script src="/media/jui/js/jquery-migrate.min.js?2e60e68fb95354eb9c457ede7e3eb866"></script> <script src="/media/jui/js/bootstrap.min.js?2e60e68fb95354eb9c457ede7e3eb866"></script> <script src="/media/regularlabs/js/script.min.js?v=17.5.1388"></script> <script src="/media/betterpreview/js/script.min.js?v=5.0.1"></script> <script src="/media/plg_system_sl_scrolltotop/js/scrolltotop_jq.js"></script> <script src="/media/system/js/core.js?2e60e68fb95354eb9c457ede7e3eb866"></script> <script src="/media/system/js/keepalive.js?2e60e68fb95354eb9c457ede7e3eb866"></script> <script> jQuery(function($){ $(".hasTooltip").tooltip({"html": true,"container": "body"}); }); jQuery(document).ready(function() {

jQuery(document.body).SLScrollToTop({

	'image':		'',

	'text':			'Back to top',

	'title':		'Back to top',

	'className':	'scrollToTop',

	'duration':		500

});

});
</script>

<script type="text/javascript"> /* */ </script>

@ObsessedGamer Please report the issue to JoomlaXTC support.

Set to "closed" on behalf of @franz-wohlkoenig by The JTracker Application at issues.joomla.org/joomla-cms/16096

closed as no Core Issue.

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_{This comment was created with the J!Tracker Application at issues.joomla.org/tracker/joomla-cms/16096.}

This may help https://github.com/renekreijveld/JoomlaJsonCheck

Thank you for the help guys & Brian I am going to checkout that link, thanks!