hello, first please make sure that the date & time is set correctly on your system. if this doesn't solve the issue (or it is already set properly), a possible solution depends on different factors:

• what is the error code shown under technical details on the error page?

in case the error code equals sec_error_unknown_issuer, please attempt to add an exception on the bottom of the error page & inspect the certificate (see the screenshot attached for instructions):

• which issuer information does the certificate contain?

please report back with this information. thank you!

"This Connection is Untrusted" error message appears - What to do

Hi Philip

Thanks for the swift response.

Unfortunately it does not solve the problem.

Date and time are correct on the Windows machine.

The error code shown is sec_error_unknown_issuer.

When adding an exception, I got the following information:

The site uses an invalid security certificate.

The certificate is not trusted because no issuer chain was provided.

(I was not offered the option to look at the certificate.)

The article suggests that I disable any SSL scanning in my security software. I checked the security software - the standard sofware that comes with Windows 8.1 - and couldn't find any reference to SSL scanning.

However, I started off Internet Explorer on the same machine and this doesn't have the same problem, so I think the issue is Firefox-related.

(My version on Windows is Firefox 27.0.1).

I also deleted the cert8 db file from my personal folder in case this had got corrupted, but this did not help.

Thanks again for your efforts. cranwej

Can you check who is the issuer of the certificate?

You can retrieve the certificate and check details like who issued certificates and expiration dates of certificates.

• Click the link at the bottom of the error page: "I Understand the Risks"

Let Firefox retrieve the certificate: "Add Exception" -> "Get Certificate".

• Click the "View..." button and inspect the certificate and check who is the issuer of the certificate.

You can see more Details like intermediate certificates that are used in the Details pane.

Thanks, cor-el.

I did as you suggested and got the information on the Security Certificate.

The issuer is called "fiddler2" - I don't know if that is a trustworthy site or not - and whether it is or not, I don't know what I can do about it.

Details are listed below, I hope that they mean something.

Cranwej

The details are:

bank.barclays.co.uk
Identity: bank.barclays.co.uk
Verified by: #0044004F005F004E004F0054005F00540052005500530054005F0046006900640064006C006500720052006F006F0074
Expires: 12/02/24

Subject Name
OU (Organisational Unit):	Created by http://www.fiddler2.com
O (Organisation):	#0044004F005F004E004F0054005F00540052005500530054
CN (Common Name):	bank.barclays.co.uk
Issuer Name
OU (Organisational Unit):	Created by http://www.fiddler2.com
O (Organisation):	#0044004F005F004E004F0054005F00540052005500530054
CN (Common Name):	#0044004F005F004E004F0054005F00540052005500530054005F0046006900640064006C006500720052006F006F0074
Issued Certificate
Version:	3
Serial Number:	F3 49 24 F5 EC 6A 1F 91 46 7C 10 03 1C 09 89 DA
Not Valid Before:	2014-02-13
Not Valid After:	2024-02-12
Certificate Fingerprints
SHA1:	6A 78 19 3D 5C 5B 6F EE ED A1 96 59 7E EA CA BB C7 A7 B8 61
MD5:	F9 F4 AB 65 68 26 06 5A 00 23 AC 40 83 2C 14 87
Public Key Info
Key Algorithm:	RSA
Key Parameters:	05 00
Key Size:	1024
Key SHA1 Fingerprint:	C7 4F 60 10 79 97 3D 10 ED A9 79 1B 87 AC 1A 07 F5 10 69 97
Public Key:	30 81 89 02 81 81 00 87 5A A5 4D BD 30 E1 A7 4E B8 F4 23 DB 9E 17 3B 51 0C 52 F5 DF 40 72 A7 7C 3C E4 A2 05 71 BF F7 36 AC D9 A6 33 4F D6 5A D4 96 34 AD 8C 3B 61 7D 17 FC 98 E0 4E 10 31 90 6E 81 03 EA 83 2F D1 78 C1 93 CE FA D3 42 97 C2 0B BC A6 C5 BA F0 90 37 2A 27 D3 60 83 22 8F 58 DB A2 BA FF 5D F4 47 E5 EE 01 A4 3D 1F 74 F1 03 19 B8 D9 19 42 E4 E1 11 05 A6 68 17 9E F8 B0 DB 21 AA 53 4F C3 AF CB 6F 02 03 01 00 01
Basic Constraints
Certificate Authority:	No
Max Path Length:	Unlimited
Critical:	Yes
Extended Key Usage
Allowed Purposes:	Server Authentication
Critical:	No
Extension
Identifier:	2.5.29.1
Value:	30 81 B5 80 10 EA 1E C6 0E A9 26 C3 40 EA 30 06 EE 3B 84 21 1C A1 81 8E 30 81 8B 31 2B 30 29 06 03 55 04 0B 13 22 43 72 65 61 74 65 64 20 62 79 20 68 74 74 70 3A 2F 2F 77 77 77 2E 66 69 64 64 6C 65 72 32 2E 63 6F 6D 31 21 30 1F 06 03 55 04 0A 1E 18 00 44 00 4F 00 5F 00 4E 00 4F 00 54 00 5F 00 54 00 52 00 55 00 53 00 54 31 39 30 37 06 03 55 04 03 1E 30 00 44 00 4F 00 5F 00 4E 00 4F 00 54 00 5F 00 54 00 52 00 55 00 53 00 54 00 5F 00 46 00 69 00 64 00 64 00 6C 00 65 00 72 00 52 00 6F 00 6F 00 74 82 10 CB 0A 8C 2E BD 0C 3A 9A 42 CD 09 9A BF 0A 2E FA
Critical:	No
Signature
Signature Algorithm:	1.3.14.3.2.29
Signature Parameters:	05 00
Signature:	B4 EE 9E 2D 86 1D 38 BA 92 0D 28 BC FF 09 E0 62 2D 32 27 DD CA 40 A6 38 62 F0 57 A2 C9 24 3C 12 9D C6 95 0C 64 0D 35 43 D0 7A 03 E3 A8 E3 C2 A8 BE 09 69 10 B6 5E C2 15 A3 08 A6 2B 40 8A A7 B8 B8 CA B6 E4 C1 CB AF BC A4 2B EE 06 6D C6 2E 56 F6 E4 F1 15 60 F0 E7 75 2B FF 59 F5 31 B6 44 78 C4 89 68 43 BB 1F 9F 1D 88 6A 99 3E 76 F3 06 F2 C8 9F 73 78 18 C8 2C 72 54 BE CF FC E4 B0 5C C3

unfortunately the fiddler2 issuer in certificates might be a sign of unwanted software present on your pc that is intercepting secure network traffic. please go into the system control panel and uninstall programs like BrowserSafeguard, BrowserSafe, SafeGuard or other software that sounds suspicious and didn't get installed by you intentionally.
_{reference: https://support.mozilla.org/en-US/questions/982532#answer-520145}

afterwards, run a full scan of your system with different security tools like the free version of malwarebytes & adwcleaner.

Troubleshoot Firefox issues caused by malware

Hi Philip

Thanks again for the swift response.

I will follow your advice.

This will take a little time, because the laptop is new, it's touch-screen rather than the mouse and keyboard I am used to, it is Windows 8.1 where my previous Windows experience is XP, and the laptop came with Windows pre-installed and a host of other software. I don't know which of this other software is crap - I suspect most or all of it, but finding out will be a learning experience.

You have given me confience that there is a solution, somwhere!

Best wishes and thanks, cranwej

Yes you can download the malwarebytes and scan for the errors you can alos get the latest malwarebytes here

Free Download Malwarebytes

or another spyware are adware remover

SUPERAntiSpyware

download this tools and scan your Pc once you will get rid of the problems

moderator edited the hyperlink for MalwareBytes to the official source, same for Super Anti Spyware

Thanks everyone - my problem is finally solved.

I cleared out all of the pupware. It took some time, because I have never used Windows 8 before and I was never too sure if a piece of software that popped up was an importantor useful part of Windows or just something the HP had chosen top bundle in with my new Windows 8 PC.

Having cleared out all of the rubbish, I ran Malware which found some more issues and ealt with them.

At this point, I tried to use my browser again to access the internet. If failed again, but with a different error - my PC was using a Windows proxy server!

I don't know how thgis got switched on - I'd never even heard of a proxy server before then.

However, a Google search showed me how to switch off the proxy server, and I was back in business.

Many thanks to all of you kind people who helped me.

John