* *Missing key for encryption*: there is probably a key selected in FairEmail that does not exist in the OpenKeychain app anymore. Resetting the key (see above) will probably fix this problem.
* *Key for signature verification is missing*: the public key for the sender is not available in the OpenKeychain app. This can also be caused by Autocrypt being disabled in the encryption settings or by the Autocrypt header not being sent.
* *OpenPgp error 0: null* / *OpenPgp error 0: General error*: please check the key in the OpenKeychain app and make sure there are no conflicting identities for the key and make sure the email address exactly matches the key, including lower/upper case. Also, make sure the key can be used to sign/encrypt and isn't for encrypting/signing only.
* *OpenPgp error 0: Encountered an error reading input data!*: your public key has the [AEAD](https://en.wikipedia.org/wiki/Authenticated_encryption) flag set, but the message was encrypted in the older MDC (Modification Detection Code) mode by the sender. For example the Posteo email server does this erroneously. Workaround: remove the AEAD flag from the public key.
* *OpenPgp error 0: Encountered an error reading input data!*: your public key has the [AEAD](https://en.wikipedia.org/wiki/Authenticated_encryption) flag set, but the message was encrypted in the older MDC (Modification Detection Code) mode by the sender. For example the Posteo email server does this erroneously. Workaround: [remove the AEAD flag](https://github.com/keybase/keybase-issues/issues/4025#issuecomment-853933127) from the public key.
**Important**: if *Don't keep activities* is enabled in the Android developer options,
FairEmail and the OpenKeychain app cannot run at the same time, causing PGP operations to fail.
M66B
2 years ago