Hi,

recently my notebook had to be reinstalled and now trying to set up my Zotero library again on Windows 10 using the latest Zotero version. Unfortunately I have no backup of the Zotero library but I do have all the pdfs. I tried importing them but Zotero was only able to retrieve the complete metadata from about half of the files. For the other files it either didn't find the year (which has never happened to me before) or it couldn't retrieve any information at all with error messages being that it didn't find any reference or that it couldn't read the pdf. I know that this can happen from time to time but it happened for a large amount of well-formatted recent published pdfs with the doi on the front page. Another strange thing: When I use the identifier and type the doi of these papers in manually I rarely get a result on the first try but sometimes on the second.

Do you have any idea what could cause this problem?

Thanks in advance.