Error: message: Signing could not be verified. -260.
This is essentially the solution:
ENABLE THE VERFICATION ON CERTIFICATE
- Start Firefox (if it isn’t already). This assumes FireFox version 3+ so menu item names below may differ for other FireFox versions but you should be able to browse to something that has a list of certificates (See image below).
- Go to Edit -> Preferences. New panel appears.
- On the new panel, click Advanced category followed by the Encryption tab then View Certificates button.
- Browse down to VeriSign certificates. You may see something similar to the below:
- Notice in the above image the highlighted certificate "Verisign Class 3 Public Primary Certification Authority" I’ve chosen. It matches exactly what we got highlighted in orange earlier in step 6 from first part above.
- Click Edit on the highlighted. You should be presented with three choices:
This certificate can identify web sites.
This certificate can identify mail users.
This certificate can identify software makers.
- Check off "This certificate can identify software makers."
- Click Ok to save then Ok on other open panels or Save as the case may be and restart FireFox.
- Try to download your extension again. The error should be gone.
- You’re done!
There Verisign was the verificator.
But which is the verifier for Adblock?
Here I found the answer : StartCom. everywhere you read Verisisgn replace it by Start.com and youŕe done.