diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4d520963..80c3fea3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,7 @@
+### 1.49.1 - 2026-03-??
+- Fix Filter parseValue method incorrectly handling invalid JSON values
+  - GH Issue 948: Multi value text choice filters don't work for JSON values, crash the app
+
 ### 1.49.0 - 2026-03-10
 - Update TypeScript compiler `lib` option to `"ES2023"'
 - Add `declarationMap` and `outDir` to TypeScript compiler options
diff --git a/package-lock.json b/package-lock.json
index 22a20a4a..a5989e00 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "@labkey/api",
-  "version": "1.49.0",
+  "version": "1.49.1-fb-gh-948.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "@labkey/api",
-      "version": "1.49.0",
+      "version": "1.49.1-fb-gh-948.0",
       "license": "Apache-2.0",
       "devDependencies": {
         "@babel/core": "7.29.0",
diff --git a/package.json b/package.json
index 527cffa0..10505d51 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@labkey/api",
-  "version": "1.49.0",
+  "version": "1.49.1-fb-gh-948.0",
   "description": "JavaScript client API for LabKey Server",
   "scripts": {
     "build": "npm run build:dist && npm run build:docs",
diff --git a/src/labkey/filter/Types.spec.ts b/src/labkey/filter/Types.spec.ts
index 248440ee..f1c7ac69 100644
--- a/src/labkey/filter/Types.spec.ts
+++ b/src/labkey/filter/Types.spec.ts
@@ -51,3 +51,45 @@ describe('Types', () => {
         expect(generateFilterTypesSnapshot(Types)).toStrictEqual(typesSnapshot);
     });
 });
+
+describe('parseValue', () => {
+    describe('multi value types', () => {
+        it('should parse JSON formatted values', () => {
+            const type = Types.IN;
+            const value = '{json:["value1","value2","value;3"]}';
+            expect(type.parseValue(value)).toEqual(['value1', 'value2', 'value;3']);
+        });
+
+        it('should split values by the type multi-value separator', () => {
+            const semicolonType = Types.IN; // Uses ';' as separator
+            const semicolonValue = 'value1;value2;value3';
+            expect(semicolonType.parseValue(semicolonValue)).toEqual(['value1', 'value2', 'value3']);
+
+            const commaType = Types.BETWEEN; // Uses ',' as separator
+            const commaValue = 'value1,value2';
+            expect(commaType.parseValue(commaValue)).toEqual(['value1', 'value2']);
+        });
+
+        it('should split values by newline separator', () => {
+            const type = Types.IN;
+            const value = 'value1\nvalue2\nvalue3';
+            expect(type.parseValue(value)).toEqual(['value1', 'value2', 'value3']);
+        });
+
+        it('should split values by both type separator and newline', () => {
+            const type = Types.IN;
+            const value = 'value1;value2\nvalue3';
+            expect(type.parseValue(value)).toEqual(['value1', 'value2', 'value3']);
+        });
+
+        it('should fall back to regex parsing if JSON is invalid', () => {
+            const type = Types.IN;
+            // Invalid JSON: missing closing quote for value2
+            const singleValue = '{json:["value1","value2]}';
+            expect(type.parseValue(singleValue)).toEqual([singleValue]);
+
+            const multiValue = '{json:aaa;bb}';
+            expect(type.parseValue(multiValue)).toEqual(['{json:aaa', 'bb}']);
+        });
+    })
+});
\ No newline at end of file
diff --git a/src/labkey/filter/Types.ts b/src/labkey/filter/Types.ts
index fa78dd15..e81225e2 100644
--- a/src/labkey/filter/Types.ts
+++ b/src/labkey/filter/Types.ts
@@ -13,7 +13,7 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-import { isArray, isString } from '../Utils';
+import { isString } from '../Utils';
 
 import { FilterValue, multiValueToSingleMap, oppositeMap, singleValueToMultiMap } from './constants';
 
@@ -557,6 +557,22 @@ export function getFilterTypesForType(jsonType: JsonType, mvEnabled?: boolean):
     return types;
 }
 
+// Note that while ';' and ',' are both used as primary separators, '\n' is the only secondary separator
+const NEW_LINE_SEP = '\n';
+
+export function parseMultiValueFilterString(type: IFilterType, value: string) {
+    if (value.indexOf('{json:') === 0 && value.indexOf('}') === value.length - 1) {
+        try {
+            return JSON.parse(value.substring('{json:'.length, value.length - 1));
+        } catch {
+            // GH Issue #948 Purposely do nothing, revert to parsing with regex
+        }
+    }
+
+    const regexPattern = new RegExp(`[${NEW_LINE_SEP}${type.getMultiValueSeparator()}]`);
+    return value.split(regexPattern);
+}
+
 /**
  * Creates a FilterType object and stores it in the global URL Map used by Filter.getFilterTypeForURLSuffix
  * @param displayText The text to display in a filter menu
@@ -585,8 +601,6 @@ export function registerFilterType(
     const isDataValueRequired = () => dataValueRequired === true;
     const isMultiValued = () => multiValueSeparator != null;
     const isTableWise = () => tableWise === true;
-    // Note that while ';' and ',' are both used as primary separators, '\n' is the only secondary separator
-    const NEW_LINE_SEP = '\n';
 
     const type: IFilterType = {
         getDisplaySymbol: () => displaySymbol ?? null,
@@ -606,15 +620,10 @@ export function registerFilterType(
         parseValue: value => {
             if (type.isMultiValued()) {
                 if (isString(value)) {
-                    if (value.indexOf('{json:') === 0 && value.indexOf('}') === value.length - 1) {
-                        value = JSON.parse(value.substring('{json:'.length, value.length - 1));
-                    } else {
-                        const regexPattern = new RegExp(`[${NEW_LINE_SEP}${type.getMultiValueSeparator()}]`);
-                        value = value.split(regexPattern);
-                    }
+                    value = parseMultiValueFilterString(type, value);
                 }
 
-                if (!isArray(value))
+                if (!Array.isArray(value))
                     throw new Error(
                         "Filter '" +
                             type.getDisplayText() +
@@ -625,7 +634,7 @@ export function registerFilterType(
                     );
             }
 
-            if (!type.isMultiValued() && isArray(value))
+            if (!type.isMultiValued() && Array.isArray(value))
                 throw new Error("Array of values not supported for '" + type.getDisplayText() + "' filter: " + value);
 
             return value;
@@ -636,7 +645,7 @@ export function registerFilterType(
                 return '';
             }
 
-            if (type.isMultiValued() && isArray(value)) {
+            if (type.isMultiValued() && Array.isArray(value)) {
                 // 35265: Create alternate syntax to handle semicolons
                 const sep = type.getMultiValueSeparator();
                 const found = value.some((v: string) => {