Found a solution!
We use the following environment:
Windows Server 2012 R2
Jenkins Version 1.652
Subversion PlugIn 2.5.7
SVN 1.8
Our SVN repository includes several externals.
We figure out, this leads to the "ISVN authentication error". For a "nomal" repository the error does not occur.
Here the solution:
We use "Addition Credentials" in Source-Code-Management job settings.
In the Realm field the string must look like "<https://server-hostname:443> Authorization SVN".
The last words "Authorization SVN" are importent.
In the Credentials field we use the same as for the repository.
After we used this settings, the error went away.
sathishkumar Please, provide more detailed information. This is not blocker at all.