404s clinging on in Search Console

[MickEdwards]

What is a reasonable length of time to expect 404s to be resolved in Search Console?  There was a mass of 404s that were built up from directory changes and filtering URLs that have been fixed.  These have all been fixed but of course there are some that slipped the net.  How long is it reasonable to expect the old 404s that don't have any links to drop away from Search Console?  New 404s are still being reported over 4 months later.  'First detected' is always showing as a date later than the fixed 404's date.

Is this reasonable, i've never seen this being so resilient and not clean up like this?  We manually fix these 404s and like popcorn more turn up.

Just to add the bulk of 404s came into existence around a year ago and left for around 8 months.

[benesmartin]

Hey Michael,

I've found some other threads about the same issue. You can check them, maybe it could help:
https://moz.com/community/q/how-long-will-404-errors-show-in-webmaster-tools-search-console https://productforums.google.com/forum/#!topic/webmasters/hupstYVfBzo

Best, Martin