Alide Folz 

I think you must provide more information than this to get a sensible answer.

1. what file format is the original format of each file?
2. what happened when you created your project or added the files to it?  Were both files recognised as translatable, or as reference files?

pdf-format 

How I recognide as is refence file? Normaly, I have xliff-file

Alide Folz 

When you add the source files to your project it will show in the user interface, like this for example:

Alide Folz said:

pdf-format 

So you added two PDF files to your project and one of them won't convert to an sdlxliff?  Is this what you are saying?  Can you open the one that would not convert in Studio if you only work with that file?  Can you open it as a PDF in Adobe Acrobat Reader?

Alide Folz 

When you add the source files to your project it will show in the user interface, like this for example:

Alide Folz said:

pdf-format 

So you added two PDF files to your project and one of them won't convert to an sdlxliff?  Is this what you are saying?  Can you open the one that would not convert in Studio if you only work with that file?  Can you open it as a PDF in Adobe Acrobat Reader?

Hier handelt sich nicht um ein Neuprojekt, sondern hinzufügen einer neuen Datei zum bestehenden Projekt: Die eine wurde umgewandelt in xliff, die zweite nicht.

Alide Folz 

Indeed... you need to be a detective to work out what you're doing :-)  I now believe this thread is actually the same as this one:  Trados Studio 2022: Batch Tasks so if you agree I'll close this one so we don't have to maintain separate discussions on the same subject?

Gerne. Auch ich will kein Detektiv sein, um zu verstehen, was in den Köpfen der Programmierer vorgeht. Meine Aufgaben sind zu linguistisch.