Magento 1.9.3.9 problem with signature only at the last step of OAuth?

[ventorwrtoac39]

I'm using PLAINTEXT method and I do get through all steps of OAuth but the last one (/oauth/token?....). Response is allways "oauth_problem=signature_invalid" despite all previous steps accepted the same PLAINTEXT signature "CONSUMER_SECRET&" (or in URI terms: "CONSUMER_SECRET%26")

Does this specific Magento version have bug or am I missing something?

[Manish Mittal]

Hello @ventorwrtoac39 

Try below shared links if you can get some solution, its seems same issue here:

https://magento.stackexchange.com/questions/147319/error-oauth-problem-signature-invalid-for-post

https://ipfs-sec.stackexchange.cloudflare-ipfs.com/magento/A/question/31806.html