Interraction between Middlewares errors + basicauth

I use a basicauth middleware for access to the traefik api.
If I use it alone, it works fine.
but if I use it with errors middleware that redirects 401 errors, the basicauth do not show any login prompt and just throw a 401 error from the errors middleware
the router:

"routers":{
	"api@file":{
		"entryPoints":["websecure"],
		"middlewares":["errorpage@file","ipwhitelist@file","minikea@file"],
		"service":"api@internal",
		"rule":"Host(`traefik.minikea.org`)",
		"tls":{"certResolver":"OVH"},
		"status":"enabled",
		"using":["websecure"]}}

the middlewares:

"middlewares":{
	"minikea@file":{
		"basicAuth":{"users":["minikea:$apr1$CS/5oASo$xG7nYzCWksMj.1TD0sfet1"]},
		"status":"enabled",
		"usedBy":["api@file"]},
	"errorpage@file":{
		"errors":{"status":["401-404"],"service":"fallback","query":"/{status}.jpg"},
		"status":"enabled",
		"usedBy":["api@file"]},
	"ipwhitelist@file":{
		"ipWhiteList":{"sourceRange":["127.0.0.1/32","192.168.1.0/24","172.19.0.1"]},
		"status":"enabled",
		"usedBy":["api@file"]}

logs:

traefik    | time="2020-01-22T13:08:09Z" level=debug msg="Handling connection from xx.xx.xx.xx:30532"
traefik    | time="2020-01-22T13:08:10Z" level=debug msg="Authentication failed" middlewareName=minikea@file middlewareType=BasicAuth
traefik    | time="2020-01-22T13:08:10Z" level=error msg="Caught HTTP Status Code 401, returning error page" middlewareName=errorpage@file middlewareType=customError

if I remove the errors middleware, I have this kind of logs:
incorrect login:

traefik    | time="2020-01-22T13:12:28Z" level=debug msg="Authentication failed" middlewareName=minikea@file middlewareType=BasicAuth
traefik    | time="2020-01-22T13:12:33Z" level=debug msg="Authentication failed" middlewareName=minikea@file middlewareType=BasicAuth

correct login :

traefik    | time="2020-01-22T13:12:44Z" level=debug msg="Authentication failed" middlewareName=minikea@file middlewareType=BasicAuth
traefik    | time="2020-01-22T13:12:49Z" level=debug msg="Authentication succeeded" middlewareName=minikea@file middlewareType=BasicAuth

the first 401 response should not be transfered to the second middleware or there should not be a first 401 response in the first place.

If I pass the username:password in the url, the behavior is exactly the same.

Nobody have tested that?
Is there someone who can explain what is wrong?

Where is the basicauth's expiration defined?

What do you mean by expiration?

@Minikea how long is a browser session authenticated for - and where can that be altered?

I don't know but why do you hijack my post to ask your question?