Cannot upload to Prusa Connect - PrusaSlicer

RE: Cannot upload to Prusa Connect

Wilts01 — Sat, 10 Jan 2026 20:43:37 +0000

I have found the issue. It appears to be something with my home network since if I use Proton VPN them it works fine. So somehow my erro router is blocking the connection.

Thanks for all the suggestions

Paul

RE: Cannot upload to Prusa Connect

Wilts01 — Wed, 07 Jan 2026 21:29:13 +0000

A bit more fault finding. At the suggestion of Prusa support I set the printer to have a static IP. No change, same error. I also tried removing the printer and adding it again. No change, same error.

Prusa Link appears in my webbrowser but none of the functionality works. I can upload files from the Prusa Phone App.

I'll continue asking Prusa support for help

RE:

NickAtNight — Sun, 21 Dec 2025 17:30:16 +0000

Have you tried the PrUSA Link instead of the PrUSA Connect?

One way is to use the browser, go to the printer address. Log in. Then upload the file.

Also, does it work by the PrUSA phone app?

It used to work on my iMac but it doesn't look as it has ever worked on my new Mac Studio

RE: Cannot upload to Prusa Connect

NickAtNight — Sun, 21 Dec 2025 17:22:59 +0000

You are getting a different error than U was getting.

——

“The error "SSLRead() return error -9820" typically indicates a network-level issue during an SSL/TLS handshake, often related to a poor or unstable internet connection. This error commonly occurs when attempting to push large files to remote repositories via HTTPS, such as with GitHub or BitBucket, and is frequently associated with timeouts or interruptions in the data transfer process.”

”SSL (Secure Sockets Layer) is a security protocol designed to ensure privacy, authentication, and data integrity in internet communications. It encrypts data transmitted between a web browser and a server, preventing unauthorized access or tampering. SSL has been succeeded by TLS (Transport Layer Security), though the term "SSL" is still commonly used.”

RE: Cannot upload to Prusa Connect

Wilts01 — Sun, 21 Dec 2025 15:40:54 +0000

Thanks for the reply. I looked at the Local Network security settings and that was already set. So it must be something else.

It used to work on my iMac but it doesn't look as it has ever worked on my new Mac Studio which is a copy of the iMac. I'll put a request into tech support.

RE:

NickAtNight — Sat, 20 Dec 2025 22:53:21 +0000

Have you previously connected successfully?

PrUSA tech support recently helped me get my PrUSA Slicer connected via PrUSA Link to my CoreONE printer. The secret issue turned out to be the built in Apple Security.

I had to go to Settings/ Privacy & Security / Local Network and allow PrUSA Slicer to access the Network. Also to allow VLC to access the Network for the Camera.

That was a real head slapper once the PrUSA tech guy reminded me about the Apple Network Security. The second problem was a typo in the connect password...

Remember: PrUSA Connect is via the Cloud. That is not a Network connection. PrUSA Link is the Network connection.

Posted by: @wilts01

I'm running Prusaslicer 2.94 on a Mac Studio running macOS 26.1. When I try to upload a sliced model from Prusaslicer to Prusa Connect, I get the error message :
Error uploading to print host:

Failure when receiving data from the peer:

SSLRead() return error -9820
I get a similar bug on my MacBook Pro.

The Prusa Connect tab works - I can control the printer etc. It's just I can't upload the G code from the button on the front page.

Any suggestions on how to fix it?

Thanks Paul

Cannot upload to Prusa Connect

Wilts01 — Sat, 20 Dec 2025 16:41:16 +0000

I'm running Prusaslicer 2.94 on a Mac Studio running macOS 26.1. When I try to upload a sliced model from Prusaslicer to Prusa Connect, I get the error message :

Error uploading to print host:

Failure when receiving data from the peer:

SSLRead() return error -9820

I get a similar bug on my MacBook Pro.

The Prusa Connect tab works - I can control the printer etc. It's just I can't upload the G code from the button on the front page.

Any suggestions on how to fix it?

Thanks Paul