HTTP 409 Conflict error

[oeway]

Hi, I am testing ImageJ-server with the pyimagej client, but I constantly get this HTTP 409 Conflict with this line: ij.show(img_in, format='jpg'). And if I change the format to 'png' or 'tif' then no error.

If I use the browser to visit the url:

1. http://localhost:8080/objects/object:jyrqyqekjp1oh1yz/ gives me {"id":"object:jyrqyqekjp1oh1yz","created_at":"Wed Jul 31 23:13:14 CEST 2019","created_by":"uploadFile:filename=2D_1_MMStack_1-Pos_000_000.ome-0001.tif","last_used":"Wed Jul 31 23:13:15 CEST 2019","class":"net.imagej.DefaultDataset"}

2. http://localhost:8080/objects/object:jyrqyqekjp1oh1yz/jpg causes error:
   {"code":409,"message":"HTTP 409 Conflict"}

3. http://localhost:8080/objects/object:jyrqyqekjp1oh1yz/png opens a png image.

I am using ImageJ 1.52p with Java 1.8.0 on MacOS 10.14.5.