Document necessary error code processing
@@ -469,6 +469,18 @@ Remove your usage of the low level APIs. In this case you will need to rewrite y
=back
+=head3 Error code changes
+
+As OpenSSL 3.0 provides a brand new Encoder/Decoder mechanism for working with
+widely used file formats, application code that checks for particular error
+reason codes on key loading failures might need an update.
+
+Password-protected keys may deserve special attention. If only some errors
+are treated as an indicator that the user should be asked about the password again,
+it's worth testing these scenarios and processing the newly relevant codes.
+
+There may be more cases to treat specially, depending on the calling application code.
+
=head2 Upgrading from OpenSSL 1.0.2
Upgrading to OpenSSL 3.0 from OpenSSL 1.0.2 is likely to be significantly more
