Content blocked because it was not signed by a valid security certificate.

Question

Hello @Elsie Lu_MSFT ,@Emily Du-MSFT ,

i'm bloqued with this issue when i try to see the application in SharePoint 2013 they give me this message 'Content blocked because it was not signed by a valid security certificate.' i try to put my site as trusted site but without result and also clear ssl certificat but the same issue

any solution please

Answer 1

@El Mehdi Ajraou To narrow down this issue, let's verify the following firstly:

1. What is "Application" in your question? Is it a site collection of a web application?
2. Do you enable SSL on your web application?
3. Please check if other site collections/sites or web applications have this issue. If other site collections don't have this issue, please compare the differences between them.
4. Does this issue happen using different browsers? Like IE, Edge, Chrome.
5. Do other users have this issue?

You mentioned that you have put your site as trusted site, when you did the action, please check if you disable the following setting. If not, please do that, restart your computer, then test again, compare the result.

Updated:
Please try the following if the above doesn't work:

1. Press Tools in internet explorer
2. Press the Advanced tab and unchecked the 'Warn about certificate address mismatch' option
3. Press Apply and OK
4. Restart the computer.
   

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Answer 2

is SSL certificate valid (not expired, not self-signed)? If it is not - web browsers will continue show errors because this is default behavior.
Also did you try to open the same web app in other browsers (FF or Chrome)?

Answer 3

I followed the steps that worked for me.

1. Go to Drive C>> Users
2. Open the folder named according to your username
3. Find the folder named ".office-addin-dev-certs "
4. Delete the folder
5. Next time trying to run an Add-In will ask you to install a certificate, Accept it.
   Hope this will solve the security certificate issue.