If you are getting an error like “SSF error : invalid signer” while trying to send certificate in transaction code “OAC0″ check the following step to solve it…

Situation should be look like below screen when you try to send certificate in transaction OAC0

To solve the issue  , go to transaction STRUST and check your “System PSE” status , if look like below output then you need to recreate again

Right click –> Replace

Check and confim the following screen

Continue with YES

Now STRUST should be look like GREEN for the “System PSE”

Now it’s time to try again “Sending Certificate” on the tcode OAC0

and i hope you will get the same result like mine…”Certificate Sent Successfully”