Knowledge Base

Explanation of error " Received fatal alert: certificate_unknown"

When connecting to a Neo4j instance with the Neo4j Browser, the following error may be logged in the $NEO4J_HOME\logs\debug.log

2020-06-20 13:33:13.039-0400 ERROR [o.n.b.t.TransportSelectionHandler] Fatal error occurred when initialising pipeline: [id: 0x59d02719, L:/ ! R:/] Received fatal alert: certificate_unknown
io.netty.handler.codec.DecoderException: Received fatal alert: certificate_unknown
	at io.netty.handler.codec.ByteToMessageDecoder.callDecode(
	at io.netty.handler.codec.ByteToMessageDecoder.channelInputClosed(
	at io.netty.handler.codec.ByteToMessageDecoder.channelInputClosed(
	at io.netty.handler.codec.ByteToMessageDecoder.channelInactive(
	at io.netty.handler.ssl.SslHandler.channelInactive(

This is usually as a result of either a bad certificate recorded at the client or incorrect url for the browser.

For example, as depicted from the screenshot and when using Google Chrome Browser and clicking on the padlock icon next to the url


you should see that this reports Certificate Valid.

Further if you click the text for Certificate Valid it should report similar to


and describe to which domain the certificate is Issued to:

If you encounter the error described above you should validate that your Neo4j Client has a valid certificate and replace at the client if not correct.