Order import failure, no feedback

Hi, is there any way to troubleshoot order imports? I can import 10 or 100 orders no problem, but 1000 or more it just fails, no import and no error. The file is uploaded and screen just returns to previous screen when setting up the import. I suspect one or more lines in the import cause this, but without error message it is impossible to find. Is there a log or something similar to use for troubleshooting?

OK, looks like there is php upload limit of 2M on my server – never mind. The error message pops up later.

Error[color=#B94A48]It is not allowed to upload files with size more than [/color]2M