My hosting provider recently upgraded the server my websites are running on and they are no longer working properly.  No images  including the site logo are being displayed and js packages such as CKeditor are not loading.  I have checked in the system log and there seem to be lots of viewstate error such as the one below.  Can anybody suggest a solution?

2022-03-02 17:46:05,605 ERROR 161.117.10.46 - en-GB - / - mojoPortal.Web.Global -  Referrer(http://warringtonql.org.uk/Secure/Login.aspx?returnurl=%2fhome.aspx) useragent Mozilla/5.0 (Windows NT 6.1; ) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/90.0.4430.85 Safari/537.36 
System.Web.UI.ViewStateException: Invalid viewstate. 

System Information

mojoPortal Version2.7.0.0 MSSQL

Operating SystemMicrosoft Windows NT 10.0.17763.0

ASP.NET Info4.0.30319.42000 Running in Full Trust

Server Time ZoneIndia Standard Time

Server Local Time(GMT 5.5) 18/03/2022 03:14:54

Greenwich Mean Time (GMT/UTC)17/03/2022 21:44:54

Feature Versions 

FeatureSchema Version

blog2.6.1.9

contactform0.0.0.6

eventcalendar0.0.0.6

feed-manager1.0.1.1

forums2.2.0.5

imagegallery0.0.0.8

kdmediaplayer1.0.0.1

linksmodule1.0.0.9

pollfeature-byChristianFredh0.0.0.5

sharedfiles1.1.0.0

superflexi0.0.1.7

surveyfeature1.9.0.0

webstore0.0.7.4

When I look at the logs for the site, every time it is trying to load an image it's throwing a 500 error - e.g.

2022-03-18 13:56:5586.5.186.3500GET /Data/Sites/1/skins/artisteer31-verticalmenu1/images/Owl.png - HTTP/2242

2022-03-18 13:56:5586.5.186.3500GET /Data/Sites/1/skins/artisteer31-verticalmenu1/images/sheet_t.png - HTTP/2242

When I run the site under IIS on my local machine it loads perfectly, but uploading it to two different hosting services (Arvixe and MilesWeb) I am getting the same problem on both - it used to work perfectly on Arvixe until they upgraded me.  What is more confusing is that one of my sites (www.merseysummerquiz.org.uk) works perfectly on both hosts.  I am very confused!

I wonder if it was just your browser caching? If the domain is the same but the backend changed it may have confused something. Cache issues are a constant cause of strange problems.

Edit: although I see Jamie tried above and he got an error too. Still, always something to try.