Hello, 

I am having a hard time with an error on two sandboxes org.

From Home, Opportunities and any other objects, i have a black cross on the background of the page and the following erreor when i scroll with my mouse. 
This error sometimes disappear by refreshing the navigator page but always come back. 
Does anione have an idea please ?

This page has an error. You might just need to refresh it. First, would you give us some details? (We're reporting this as error ID: 1568086648)
Technical stuff : 
[a.fromElement is undefined]
[79]</Ua.prototype.isEventFiredByShapeInsideTooltip()@https://naelan-software--presales.lightning.force.com/jslibrary/1642298026000/ui-analytics-reporting/EclairNG.js:999:346
[79]</Ua.prototype._onMouseLeave()@https://naelan-software--presales.lightning.force.com/jslibrary/1642298026000/ui-analytics-reporting/EclairNG.js:998:172

Hello, 

I am having a hard time with an error on two sandboxes org.

From Home, Opportunities and any other objects, i have a black cross on the background of the page and the following erreor when i scroll with my mouse. 
This error sometimes disappear by refreshing the navigator page but always come back. 
Does anione have an idea please ?

This page has an error. You might just need to refresh it. First, would you give us some details? (We're reporting this as error ID: 1568086648)
Technical stuff : 
[a.fromElement is undefined]
[79]</Ua.prototype.isEventFiredByShapeInsideTooltip()@https://naelan-software--presales.lightning.force.com/jslibrary/1642298026000/ui-analytics-reporting/EclairNG.js:999:346
[79]</Ua.prototype._onMouseLeave()@https://naelan-software--presales.lightning.force.com/jslibrary/1642298026000/ui-analytics-reporting/EclairNG.js:998:172