To work around the lack of bulk linking support (JRA-2428), I prepared a comma-separated list of issue keys, opened the "link issue" dialog and pasted the list into the issue key field. I would have expected either unmodified plain text, e.g.

ABC-17,ABC-39,DEF-20,XYZ-1

or properly separated individual issue keys like

[ABC-17 ^x] [ABC-39 ^x] [DEF-20 ^x] [XYZ-1 ^x]

However, JIRA turned the entire input into one issue key, something like this:

[ABC-17,ABC-39,DEF-20,XYZ-1 ^x]

When submitting the form, it then rejected this input, telling me an issue with the key ABC-17,ABC-39,DEF-20,XYZ-1 did not exist.

AFAIK, commas are not a valid character in issue keys, so the behavior JIRA shows does not make any sense. It should be changed to produce one of the two expected results given above.

The same problem occurs when using spaces instead of commas.