docs: add PVE version compatibility warnings across all user touchpoints

Users on unsupported PVE versions now get clear guidance at every
layer — README, install time, and GitHub release notes — rather than
silently failing or getting confusing patch errors.

- README: replace bare compatibility table with a full matrix and
  prominent callout blocks for PVE 7 (last v2.x), PVE 8 (EOL
  2026-08-31), PVE 9+ (use v3.0), and PVE ≤6 (unsupported)
- postinst: add check_pve_version() that exits on PVE < 7, warns
  loudly on PVE 7 (stay on v2.x, do not upgrade to v3.0), notes
  the PVE 8 EOL date, and warns on PVE 9+ (v2.x not supported)
- build.yml release template: add a version compatibility table so
  every GitHub release prominently states who should and should not
  install it

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.github/workflows/build.yml

@@ -315,18 +315,28 @@ jobs:
           body: |
             ## freenas-proxmox v${{ needs.build.outputs.version }}
 
-            > **Edit before publishing** — fill in tested versions below.
+            > **Edit before publishing** — fill in tested versions and remove inapplicable notices below.
 
-            ### Supported Proxmox VE Versions
+            ### ⚠️ Version Compatibility Notices
-            - Proxmox VE 8.x (tested: )
+
+            | Your Proxmox VE | What to do |
+            |:----------------|:-----------|
+            | **PVE 9+** | ❌ Do **not** install v2.x — use v3.0 when released |
+            | **PVE 8.x** | ✅ Supported. Note: PVE 8 EOL is **2026-08-31** — plan your upgrade to PVE 9 + v3.0 |
+            | **PVE 7.x** | ⚠️ Best-effort only. This is the **last v2.x release** supporting PVE 7. Do **not** upgrade to v3.0 — stay on v2.x |
+            | **PVE 6 or older** | ❌ Not supported |
+
+            ### Tested Proxmox VE Versions
+            - Proxmox VE 8.4.x (tested: )
+            - Proxmox VE 8.3.x (tested: )
             - Proxmox VE 7.x (best-effort: )
 
-            ### Supported TrueNAS Versions
+            ### Tested TrueNAS Versions
             - TrueNAS CORE:
             - TrueNAS SCALE:
 
             ### Installation
-            See [README](https://github.com/TheGrandWazoo/freenas-proxmox#installation).
+            See [README → Installation](https://github.com/TheGrandWazoo/freenas-proxmox#installation).
 
             ### Changes
             See [CHANGELOG.md](https://github.com/TheGrandWazoo/freenas-proxmox/blob/master/CHANGELOG.md#unreleased).

README.md

@@ -41,10 +41,35 @@ Proxmox VE's built-in ZFS-over-iSCSI storage type uses SSH to manage LUNs on the
 
 ## Compatibility
 
-| Plugin Version | Proxmox VE | TrueNAS CORE | TrueNAS SCALE |
+### Version Matrix
-|:--------------:|:----------:|:------------:|:-------------:|
+
-| **3.x** (upcoming) | 8.x | 13.0-U6+ | 23.10 (Cobia)+, 24.04 (Dragonfish)+ |
+| Plugin Version | Proxmox VE | TrueNAS CORE | TrueNAS SCALE | Status |
-| **2.x** (current stable) | 7.x, 8.x | 11.3+ | 22.02+ |
+|:--------------:|:----------:|:------------:|:-------------:|:------:|
+| **3.x** *(upcoming)* | 8.x, 9.x | 13.0-U6+ | Cobia (23.10)+, Dragonfish (24.04)+ | In development |
+| **2.x** *(current)* | 7.x ⚠️, 8.0–8.3 ✅, 8.4.x ✅ | 11.3+ | 22.02+ | Active |
+| **1.x** *(legacy)* | 5.x, 6.x | 11.x | — | Unsupported |
+
+### Important Version Notices
+
+> **Proxmox VE 7 users**
+>
+> v2.x is the **last release series that supports PVE 7**. PVE 7 support is best-effort only — no new patches will be developed for it.
+>
+> **Do not upgrade to v3.0** when it releases — v3.0 requires Proxmox VE 8 or later. Stay on the latest v2.x release.
+
+> **Proxmox VE 8 users**
+>
+> Proxmox VE 8 reaches **end-of-life on 2026-08-31**. Plan your upgrade to PVE 9 before that date.
+>
+> v2.x works on PVE 8. When you upgrade to PVE 9, migrate to v3.0 (coming before the EOL date).
+
+> **Proxmox VE 9+ users**
+>
+> v2.x is **not supported on PVE 9**. Use v3.0 when it is released. Do not install v2.x on a PVE 9 node.
+
+> **Proxmox VE 5 or 6 users**
+>
+> These versions are not supported. PVE 5 reached end-of-life in 2019, PVE 6 in 2022. Please upgrade your Proxmox VE installation.
 
 Check the [Releases page](https://github.com/TheGrandWazoo/freenas-proxmox/releases) for the specific Proxmox and TrueNAS versions tested against each release.
 

packaging/DEBIAN/postinst

@@ -106,11 +106,49 @@ restart_pve_services() {
     log "Done. Refresh your Proxmox browser tab to load the updated UI."
 }
 
+# Warn the user if their PVE version is outside the supported range for this
+# plugin version.  Exits non-zero (aborting the install) only for versions so
+# old that no patches exist (< 7).
+check_pve_version() {
+    local major="$1"
+
+    if [ "$major" -lt 7 ]; then
+        log "ERROR: Proxmox VE ${major}.x is not supported by this plugin."
+        log "       PVE 5 and 6 reached end-of-life in 2019 and 2022 respectively."
+        log "       Please upgrade your Proxmox VE installation before installing this plugin."
+        exit 1
+    fi
+
+    if [ "$major" -eq 7 ]; then
+        log "WARNING: *** Proxmox VE 7 — Important Notice ***"
+        log "WARNING: v2.x is the LAST release series that supports Proxmox VE 7."
+        log "WARNING: PVE 7 support is best-effort only; no new patches will be"
+        log "WARNING: developed for it."
+        log "WARNING: When v3.0 is released, DO NOT upgrade to it — v3.0 requires"
+        log "WARNING: Proxmox VE 8 or later.  Stay on the latest v2.x release."
+    fi
+
+    if [ "$major" -eq 8 ]; then
+        log "INFO: Proxmox VE 8 reaches end-of-life on 2026-08-31."
+        log "INFO: Plan your upgrade to PVE 9 and migration to v3.0 before that date."
+    fi
+
+    if [ "$major" -ge 9 ]; then
+        log "WARNING: *** Proxmox VE ${major}.x — Not Supported by v2.x ***"
+        log "WARNING: This plugin (v2.x) is not supported on Proxmox VE 9 or later."
+        log "WARNING: Patches may fail to apply or the UI may not work correctly."
+        log "WARNING: Please use v3.0 of this plugin, which is designed for PVE 9+."
+        log "WARNING: See: https://github.com/TheGrandWazoo/freenas-proxmox/releases"
+        log "WARNING: Continuing anyway — but expect problems."
+    fi
+}
+
 # ── Entry point ──────────────────────────────────────────────────────────────
 
 major=$(detect_pve_major)
 pve_mgr_minor=$(detect_pve_manager_minor)
 log "Proxmox VE major version: ${major}, pve-manager: ${pve_mgr_minor}"
+check_pve_version "$major"
 
 case "$1" in