diff --git a/css/app.css b/css/app.css
index 7e0757a10..a3abe43ab 100644
--- a/css/app.css
+++ b/css/app.css
@@ -1365,6 +1365,10 @@ thumbnail-slider img {
     overflow-y: hidden;
 }
 
+.modal-dialog pre {
+    max-height: 200px;
+}
+
 .text-weight-bold {
    font-weight: 700;
  }
diff --git a/plugin/omero_iviewer/views.py b/plugin/omero_iviewer/views.py
index 439b96375..1cfd4f2e6 100644
--- a/plugin/omero_iviewer/views.py
+++ b/plugin/omero_iviewer/views.py
@@ -23,6 +23,7 @@
 from os.path import splitext
 from collections import defaultdict
 from struct import unpack
+import traceback
 
 from omeroweb.api.api_settings import API_MAX_LIMIT
 from omeroweb.decorators import login_required
@@ -106,7 +107,14 @@ def index(request, iid=None, conn=None, **kwargs):
         if MAX_PROJECTION_BYTES > 0:
             max_bytes = MAX_PROJECTION_BYTES
 
+    try:
+        nodedescriptors = c.getConfigValue("omero.server.nodedescriptors")
+    except omero.SecurityViolation:
+        # nodedescriptors not supported in OMERO before 5.6.6 (Dec 2022)
+        nodedescriptors = None
+
     params['MAX_PROJECTION_BYTES'] = max_bytes
+    params['NODEDESCRIPTORS'] = nodedescriptors
     params['ROI_COLOR_PALETTE'] = ROI_COLOR_PALETTE
     params['SHOW_PALETTE_ONLY'] = SHOW_PALETTE_ONLY
     params['ENABLE_MIRROR'] = ENABLE_MIRROR
@@ -498,19 +506,19 @@ def image_data(request, image_id, conn=None, **kwargs):
         # Add extra parameters with units data
         # Note ['pixel_size']['x'] will have size in MICROMETER
         px = image.getPrimaryPixels().getPhysicalSizeX()
-        if (px is not None):
+        if (px is not None and 'pixel_size' in rv):
             size = image.getPixelSizeX(True)
             value = format_pixel_size_with_units(size)
             rv['pixel_size']['unit_x'] = value[0]
             rv['pixel_size']['symbol_x'] = value[1]
         py = image.getPrimaryPixels().getPhysicalSizeY()
-        if (py is not None):
+        if (py is not None and 'pixel_size' in rv):
             size = image.getPixelSizeY(True)
             value = format_pixel_size_with_units(size)
             rv['pixel_size']['unit_y'] = value[0]
             rv['pixel_size']['symbol_y'] = value[1]
         pz = image.getPrimaryPixels().getPhysicalSizeZ()
-        if (pz is not None):
+        if (pz is not None and 'pixel_size' in rv):
             size = image.getPixelSizeZ(True)
             value = format_pixel_size_with_units(size)
             rv['pixel_size']['unit_z'] = value[0]
@@ -530,8 +538,8 @@ def image_data(request, image_id, conn=None, **kwargs):
             rv['families'].append(fam.getValue())
 
         return JsonResponse(rv)
-    except Exception as image_data_retrieval_exception:
-        return JsonResponse({'error': repr(image_data_retrieval_exception)})
+    except Exception:
+        return JsonResponse({'error': traceback.format_exc()})
 
 
 @login_required()
diff --git a/src/app/context.js b/src/app/context.js
index 710f59039..8d542396f 100644
--- a/src/app/context.js
+++ b/src/app/context.js
@@ -464,6 +464,9 @@ export default class Context {
         }
         this.show_palette_only = (this.initParams[REQUEST_PARAMS.SHOW_PALETTE_ONLY] != 'False') || false
         this.enable_mirror = (this.initParams[REQUEST_PARAMS.ENABLE_MIRROR] != 'False') || false 
+        // nodedescriptors can be empty string or "None" (undefined)
+        let nds = this.initParams[REQUEST_PARAMS.NODEDESCRIPTORS];
+        this.nodedescriptors = nds == 'None' ? undefined : nds
     }
 
     /**
diff --git a/src/model/image_info.js b/src/model/image_info.js
index bdfec907b..36670eaf8 100644
--- a/src/model/image_info.js
+++ b/src/model/image_info.js
@@ -19,6 +19,7 @@
 import {noView} from 'aurelia-framework';
 import Misc from '../utils/misc';
 import Ui from '../utils/ui';
+var escapeHtml = require('escape-html')
 import {
     APP_TITLE, CHANNEL_SETTINGS_MODE, INITIAL_TYPES, IVIEWER,
     PROJECTION, REQUEST_PARAMS, WEBCLIENT, WEBGATEWAY
@@ -318,6 +319,13 @@ export default class ImageInfo {
                     this.image_id = response.id;
                 }
 
+                // validate response
+                // check for Exceptions and show error dialog.
+                const valid = this.validateImageInfo(response);
+                if (!valid) {
+                    return;
+                }
+
                 // read initial request params
                 this.initializeImageInfo(response, refresh);
                 // check for a parent id (if not well)
@@ -360,6 +368,48 @@ export default class ImageInfo {
         });
     }
 
+    /**
+     * Checks that the imgData JSON response is valid, no exceptions etc.
+     *
+     * @private
+     * @param {Object} response the response object
+     * @memberof ImageInfo
+     * @return {Boolean} True if data is valid. Also shows dialogs with errors
+     */
+    validateImageInfo(response) {
+
+        if (response.ConcurrencyException) {
+            let nds = this.context.nodedescriptors;
+            const pyramidsDisabled = nds != undefined && nds.length > 0 && !nds.includes("PixelData");
+            Ui.showModalMessage(`<p>Image is ${pyramidsDisabled ? "not" : "not currently"} viewable</p>
+                <pre>ConcurrencyException</pre>
+                <small>
+                    A pyramid of zoom levels is not available. <br>
+                    ${pyramidsDisabled ? "Pyramid generation is disabled. You will need to convert and re-import this image." :
+                     "Please contact your server Administrator if this does not resolve."} <br>
+                    See <a target="_blank" href='https://omero.readthedocs.io/en/stable/sysadmins/limitations.html#large-images'>
+                      Limitations: Large Images</a>.
+                </small>`,
+                "OK");
+            return false;
+        }
+
+        if (response.error || response.Exception) {
+            const msg = response.error || response.Exception;
+            Ui.showModalMessage(`<p>Error loading Image data</p>
+                <pre>${escapeHtml(msg)}</pre>`, "OK");
+            return false;
+        }
+
+        if (response.channels == undefined || response.channels.length === 0) {
+            Ui.showModalMessage(`<p>No channel data loaded</p>
+                <pre>${escapeHtml(JSON.stringify(response, null, 4))}</pre>`, "OK");
+            return false;
+        }
+
+        return true;
+    }
+
     /**
      * Takes the response object and assigns the bits and pieces needed
      * to the members
diff --git a/src/utils/constants.js b/src/utils/constants.js
index 4f2eb22cf..208ab6c2d 100644
--- a/src/utils/constants.js
+++ b/src/utils/constants.js
@@ -123,6 +123,7 @@ export const REQUEST_PARAMS = {
     SHAPE: 'SHAPE',
     MAPS: 'MAPS',
     MODEL: 'M',
+    NODEDESCRIPTORS: 'NODEDESCRIPTORS',
     OMERO_VERSION: 'OMERO_VERSION',
     PLANE: 'Z',
     PROJECTION: 'P',