Apache   Apache – “Size of a request header field exceeds server limit”



Symptoms

When trying to access to one of my published websites, the browser shows the following error:

Your browser sent a request that this server could not understand.
Size of a request header field exceeds server limit.

Apache - Size of a request header field exceeds server limit

Searching on the Apache debug error traces took me to this error line:

[Thu Jul 14 11:50:18 2016] [error] [client 212.86.13.12] request failed: 
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