Error while merging pdfs using pdf4me

[gagana562000]

I created a flow for merging multiple pdfs into single pdf using PD4me. First i initialized a array variable and then using get item i filter out the value i needed. Then using apply to each i took each file  content and appended it into the array variable, but after that while merging the pdfs an error was thrown saying {"errorMessage":"File could not be opened.","traceId":"d3949bd2-7a86-491f-940a-4a033fd55027"}. Can any one tell how can i solve this issue.

[gagana562000]

can anyone please suggest a solution for this asap.