I want to batch correct a URL in the MARC-Data. So I created a MARC modification templates as described in the manual (see the proxy URL example): https://koha-community.org/manual/25.05/en/html/cataloging.html#marc-modification-templates I did "Copy and replace" over "All" field(s) "856 u" to field "856 u" with Regex "s/deposit.d-nb.de/deposit.dnb.de/g" if field "856 u" matches "m/deposit.d-nb.de/" RegEx The fields in the original record look like this: 856 42 _u http://d-nb.info/1050788141/04 _3Inhaltsverzeichnis 856 42 _u http://deposit.d-nb.de/cgi-bin/dokserv?id=4659369&prov=M&dok_var=1&dok_ext=htm _3Inhaltstext 856 42 _u http://www.perlentaucher.de/buch/barbara-sichtermann/ich-rauche-zigarren-und-glaube-nicht-an-g _3Rezension After applying the template, I would expect that only the middle one gets modified. Instead I get this: 856 42 _uhttp://deposit.dnb.de/cgi-bin/dokserv?id=4659369&prov=M&dok_var=1&dok_ext=htm _3Inhaltsverzeichnis 856 42 _uhttp://deposit.dnb.de/cgi-bin/dokserv?id=4659369&prov=M&dok_var=1&dok_ext=htm _3Inhaltstext 856 42 _uhttp://deposit.dnb.de/cgi-bin/dokserv?id=4659369&prov=M&dok_var=1&dok_ext=htm _3Rezension It doesn't matter if I do "All" field(s) or "1." field(s) in the template, the result is the same. This is probably related to and maybe not the same as Bug 28231 - MARC modification template "1st" vs "Every" bug? and Bug 34508 - MARC modification templates have poor results when working with multiple of a field I think this bug is severe as it can go unnoticed and lead to data loss in a lot of records. Unnoticed because if you only have one field everything looks good and only multiple equal fields get overwritten.