KB5003173 & Fatal Error w/v2.5.2

JohnsTown55

Recently setup my Windows 10 laptop using v2.5.2 client about a week ago. Everything was working great until earlier today when I put on the latest Windows 10 update - KB5003173. My first attempt to try and connect to my VPN after the reboot resulted in it reporting this very non-specific error:

2021-05-18 16:12:27 DEPRECATED OPTION: ncp-disable. Disabling cipher negotiation is a deprecated debug feature that will be removed in OpenVPN 2.6
2021-05-18 16:12:27 WARNING: Compression for receiving enabled. Compression has been used in the past to break encryption. Sent packets are not compressed unless "allow-compression yes" is also set.
2021-05-18 16:12:27 DEPRECATED OPTION: --cipher set to 'AES-256-CBC' but missing in --data-ciphers (AES-256-GCM:AES-128-GCM). Future OpenVPN version will ignore --cipher for cipher negotiations. Add 'AES-256-CBC' to --data-ciphers or change --cipher 'AES-256-CBC' to --data-ciphers-fallback 'AES-256-CBC' to silence this warning.
2021-05-18 16:12:27 OpenVPN 2.5.2 x86_64-w64-mingw32 [SSL (OpenSSL)] [LZO] [LZ4] [PKCS11] [AEAD] built on Apr 21 2021
2021-05-18 16:12:27 Windows version 10.0 (Windows 10 or greater) 64bit
2021-05-18 16:12:27 library versions: OpenSSL 1.1.1k 25 Mar 2021, LZO 2.10
Enter Management Password:
2021-05-18 16:12:28 TCP/UDP: Preserving recently used remote address: [AF_INET]xx.xx.xx.xx:1194
2021-05-18 16:12:28 UDPv4 link local (bound): [AF_INET][undef]:0
2021-05-18 16:12:28 UDPv4 link remote: [AF_INET]xx.xx.xx.xx:1194
2021-05-18 16:12:29 WARNING: 'link-mtu' is used inconsistently, local='link-mtu 1570', remote='link-mtu 1569'
2021-05-18 16:12:29 WARNING: 'comp-lzo' is present in local config but missing in remote config, local='comp-lzo'
2021-05-18 16:12:29 [XXXXXXXXX Cert] Peer Connection Initiated with [AF_INET]xx.xx.xx.xx:1194
2021-05-18 16:12:29 open_tun
2021-05-18 16:12:29 All tap-windows6 adapters on this system are currently in use or disabled.
2021-05-18 16:12:29 Exiting due to fatal error

Tried rebooting and checking settings in the system with nothing obvious glaring out. So I ended up uninstalling and reinstalling the client again, this time everything worked fine. Anyone else run into this issue?

TinCanTech

The error is obvious.

fh29

JohnsTown55 wrote 2021-05-18 16:12:29 All tap-windows6 adapters on this system are currently in use or disabled.

Some other process or service is using your TAP adapter/driver (or the adapter is disabled).

Re-enable the adapter or stop the process using it.

If not possible, then delete the adapter completely and then reinstall openvpn which will re-create a new adapter:
https://relaxsoftwaresolutions.com/unable-to-delete-network-adapter-in-windows-10/

JohnsTown55

Interesting given I was running the laptop fine that morning, installed the update, rebooted and it started complaining about the adapter being busy.

Reinstall fixed it but I'm more curious given nothing else could have been using it why... wondering if a security change, update, etc. that the patch had that may have caused it. Unfortunately I couldn't wait to try and troubleshoot as I had to get back online and the VPN was my only way into the remote network...