Updated FAQ

FAQ.md

@@ -1072,6 +1072,7 @@ Common errors:
 * *Message signature valid but not confirmed*: the signature is okay, but the public key still needs to be confirmed in the OpenKeychain app.
 * *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](https://github.com/keybase/keybase-issues/issues/4025#issuecomment-853933127) from the key.
+* *OpenPGP error 0: An OpenPGP exception occurred during an operation."*: an imported private key is probably incompatible with the OpenKeychain app.
 
 **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.

index.html

@@ -775,6 +775,7 @@ or by installing the GitHub version of the app (as an update) and enabling insec
 <li><em>Message signature valid but not confirmed</em>: the signature is okay, but the public key still needs to be confirmed in the OpenKeychain app.</li>
 <li><em>OpenPgp error 0: null</em> / <em>OpenPgp error 0: General error</em>: 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.</li>
 <li><em>OpenPgp error 0: Encountered an error reading input data!</em>: your public key has the <a href="https://en.wikipedia.org/wiki/Authenticated_encryption">AEAD</a> 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: <a href="https://github.com/keybase/keybase-issues/issues/4025#issuecomment-853933127">remove the AEAD flag</a> from the key.</li>
+<li><em>OpenPGP error 0: An OpenPGP exception occurred during an operation.”</em>: an imported private key is probably incompatible with the OpenKeychain app.</li>
 </ul>
 <p><strong>Important</strong>: if <em>Don’t keep activities</em> is enabled in the Android developer options, FairEmail and the OpenKeychain app cannot run at the same time, causing PGP operations to fail. If needed, please <a href="https://developer.android.com/studio/debug/dev-options#enable">see here</a> about how to enable the developer options.</p>
 <p><strong>Important</strong>: Android 8.1.0 on Tecno CF8 Camon 11 Pro devices blocks communication between apps with the message “<em>AutoStart limited</em>” in the system logcat. So, FairEmail (or any other app) can’t communicate with the OpenKeychain app.</p>