PKCS12 is a encrypted container format for certificates and cryptographic keys. For encrypting the contained data multiple algorithms exists. Unfortunately not all systems processing PKCS#12 files do support all possible encryption algorithms.
When reading a PKCS#12 file by a system/program and it encounters an unsupported cryptographic algorithm you would expect an error message like "unable to read file: unknown or unsupported algorithm". Unfortunately in reality most implementations just output the generic error message "incorrect password".
Detecting the used encryption algorithm:
For detecting the used encryption algorithm execute
openssl pkcs12 -info -in example.p12
After entering the password(s) you will see the decoded data of the PKCS12 file, the encryption type can be seen by certain lines in the output.
The most recent encryption format (that is not yet supported by all programs) is used if you find a line like:
Shrouded Keybag: PBES2, PBKDF2, AES-256-CBC, Iteration 10000, PRF hmacWithSHA256
The older often called "legacy" encryption format is used if you find a line like:
Shrouded Keybag: pbeWithSHA1And3-KeyTripleDES-CBC, Iteration 1
A third even older algorithm exists. I have not found an example PKCS#12 file, but it should be output as pbeWithSHA1And40BitRC2-CBC
.
Converting a PKCS#12 file to the old encryption format
Changing the encryption type used by a PKCS#12 file is pretty complicated as you have to extract all the contained keys and certificates and the reassemble everything into a new file. The necessary openssl commands are denoted here:
https://help.globalscape.com/help/archive/secureserver3/Converting_an_incompatible_PKCS_12_format_file_to_a_compatible_PKCS_12_.htm