Hello @fa0710 thanks for your message and welcome to the forum.
If possible please answer the following questions to locate the error cause:
1) Did you use a) cryptpad.fr or b) some other CryptPad provider?
2) a) Did the export ever work or b) was this the first time you tried an export?
3) Please attach a screenshot of the whole CryptPad app including the error message. Please remember to cut private information like maybe your desktop.
Thanks.
Disclaimer:
I am NOT part of the CryptPad team and I do not speak for the CryptPad team. I am a user helping other users. I got moderation user rights for the forum from the CryptPad team to help a bit, because we all are the community, but that's all.