I have now installed Joplin Client on an iPhone and it works with my self set up Joplin Server without any problems.

With the Windows Joplin Client it works as well.

I have two android phones to test it and the sycronization does not work on both of them.

The test of the settings is positive.

I have done a Joplin update on one Android (version 2.12.2) also here always the same error message: Synchronizer: Error: uploadBlob: PUT https servername/joplin/api/items/root:/.resource/d557fbc4a77c40659945ee2f176e2e66:/content:
Error: java.security.cert.CertPathValidatorException: Trust anchor for certification path not found.

I can't find any errors in the server logs. I have already installed the certificate of the server without success.

Does anyone know the problem?

Stefan