The use of the ERROR level for this message is improper, as there is no error in the processing.
The low level SSL processing claims that the connection has not been terminated properly, hence a trailing part may be missing;
but usually the whole request has been received before connection termination and no trailing can change its meaning, hence the request is accepted (the client may just choose not to send the termination notification).
We will lower the level of this log message in the next release.