diff --git a/extensions/vscode-colorize-tests/src/colorizerTestMain.ts b/extensions/vscode-colorize-tests/src/colorizerTestMain.ts
index a29a35b1233..450e7b4874b 100644
--- a/extensions/vscode-colorize-tests/src/colorizerTestMain.ts
+++ b/extensions/vscode-colorize-tests/src/colorizerTestMain.ts
@@ -22,24 +22,31 @@ export function activate(context: vscode.ExtensionContext): any {
 			function addToken(value: string, startLine: number, startCharacter: number, length: number) {
 				const [type, ...modifiers] = value.split('.');
 
+				const selectedModifiers = [];
+
 				let tokenType = legend.tokenTypes.indexOf(type);
 				if (tokenType === -1) {
-					return;
-				}
-
-				let tokenModifiers = 0;
-				for (let i = 0; i < modifiers.length; i++) {
-					const index = legend.tokenModifiers.indexOf(modifiers[i]);
-					if (index !== -1) {
-						tokenModifiers = tokenModifiers | 1 << index;
+					if (type === 'notInLegend') {
+						tokenType = tokenTypes.length + 2;
+					} else {
+						return;
 					}
 				}
 
-
+				let tokenModifiers = 0;
+				for (const modifier of modifiers) {
+					const index = legend.tokenModifiers.indexOf(modifier);
+					if (index !== -1) {
+						tokenModifiers = tokenModifiers | 1 << index;
+						selectedModifiers.push(modifier);
+					} else if (modifier === 'notInLegend') {
+						tokenModifiers = tokenModifiers | 1 << (legend.tokenModifiers.length + 2);
+						selectedModifiers.push(modifier);
+					}
+				}
 				builder.push(startLine, startCharacter, length, tokenType, tokenModifiers);
 
-				const selectedModifiers = legend.tokenModifiers.filter((_val, bit) => tokenModifiers & (1 << bit)).join(' ');
-				outputChannel.appendLine(`line: ${startLine}, character: ${startCharacter}, length ${length}, ${legend.tokenTypes[tokenType]} (${tokenType}), ${selectedModifiers} ${tokenModifiers.toString(2)}`);
+				outputChannel.appendLine(`line: ${startLine}, character: ${startCharacter}, length ${length}, ${type} (${tokenType}), ${selectedModifiers} ${tokenModifiers.toString(2)}`);
 			}
 
 			outputChannel.appendLine('---');
diff --git a/extensions/vscode-colorize-tests/test/semantic-test/semantic-test.json b/extensions/vscode-colorize-tests/test/semantic-test/semantic-test.json
index b250b5d2bc1..1a2eeaf4408 100644
--- a/extensions/vscode-colorize-tests/test/semantic-test/semantic-test.json
+++ b/extensions/vscode-colorize-tests/test/semantic-test/semantic-test.json
@@ -4,6 +4,6 @@
 				"variable.declaration", "parameterNames",
 		"function.member.declaration",
 	"interface.declaration",
-		"function.member.declaration", "testToken.testModifier"
+		"function.member.declaration", "function.notInLegend"
 
 ]
diff --git a/src/vs/editor/common/services/semanticTokensProviderStyling.ts b/src/vs/editor/common/services/semanticTokensProviderStyling.ts
index a1cbccf4a61..e29d8f86e81 100644
--- a/src/vs/editor/common/services/semanticTokensProviderStyling.ts
+++ b/src/vs/editor/common/services/semanticTokensProviderStyling.ts
@@ -29,50 +29,65 @@ export class SemanticTokensProviderStyling {
 		let metadata: number;
 		if (entry) {
 			metadata = entry.metadata;
-		} else {
-			const tokenType = this._legend.tokenTypes[tokenTypeIndex];
-			const tokenModifiers: string[] = [];
-			let modifierSet = tokenModifierSet;
-			for (let modifierIndex = 0; modifierSet > 0 && modifierIndex < this._legend.tokenModifiers.length; modifierIndex++) {
-				if (modifierSet & 1) {
-					tokenModifiers.push(this._legend.tokenModifiers[modifierIndex]);
-				}
-				modifierSet = modifierSet >> 1;
+			if (this._logService.getLevel() === LogLevel.Trace) {
+				this._logService.trace(`SemanticTokensProviderStyling [CACHED] ${tokenTypeIndex} / ${tokenModifierSet}: foreground ${TokenMetadata.getForeground(metadata)}, fontStyle ${TokenMetadata.getFontStyle(metadata).toString(2)}`);
 			}
+		} else {
+			let tokenType = this._legend.tokenTypes[tokenTypeIndex];
+			const tokenModifiers: string[] = [];
+			if (tokenType) {
+				let modifierSet = tokenModifierSet;
+				for (let modifierIndex = 0; modifierSet > 0 && modifierIndex < this._legend.tokenModifiers.length; modifierIndex++) {
+					if (modifierSet & 1) {
+						tokenModifiers.push(this._legend.tokenModifiers[modifierIndex]);
+					}
+					modifierSet = modifierSet >> 1;
+				}
+				if (modifierSet > 0 && this._logService.getLevel() === LogLevel.Trace) {
+					this._logService.trace(`SemanticTokensProviderStyling: unknown token modifier index: ${tokenModifierSet.toString(2)} for legend: ${JSON.stringify(this._legend.tokenModifiers)}`);
+					tokenModifiers.push('not-in-legend');
+				}
 
-			const tokenStyle = this._themeService.getColorTheme().getTokenStyleMetadata(tokenType, tokenModifiers, languageId.language);
-			if (typeof tokenStyle === 'undefined') {
-				metadata = SemanticTokensProviderStylingConstants.NO_STYLING;
-			} else {
-				metadata = 0;
-				if (typeof tokenStyle.italic !== 'undefined') {
-					const italicBit = (tokenStyle.italic ? FontStyle.Italic : 0) << MetadataConsts.FONT_STYLE_OFFSET;
-					metadata |= italicBit | MetadataConsts.SEMANTIC_USE_ITALIC;
-				}
-				if (typeof tokenStyle.bold !== 'undefined') {
-					const boldBit = (tokenStyle.bold ? FontStyle.Bold : 0) << MetadataConsts.FONT_STYLE_OFFSET;
-					metadata |= boldBit | MetadataConsts.SEMANTIC_USE_BOLD;
-				}
-				if (typeof tokenStyle.underline !== 'undefined') {
-					const underlineBit = (tokenStyle.underline ? FontStyle.Underline : 0) << MetadataConsts.FONT_STYLE_OFFSET;
-					metadata |= underlineBit | MetadataConsts.SEMANTIC_USE_UNDERLINE;
-				}
-				if (tokenStyle.foreground) {
-					const foregroundBits = (tokenStyle.foreground) << MetadataConsts.FOREGROUND_OFFSET;
-					metadata |= foregroundBits | MetadataConsts.SEMANTIC_USE_FOREGROUND;
-				}
-				if (metadata === 0) {
-					// Nothing!
+				const tokenStyle = this._themeService.getColorTheme().getTokenStyleMetadata(tokenType, tokenModifiers, languageId.language);
+				if (typeof tokenStyle === 'undefined') {
 					metadata = SemanticTokensProviderStylingConstants.NO_STYLING;
+				} else {
+					metadata = 0;
+					if (typeof tokenStyle.italic !== 'undefined') {
+						const italicBit = (tokenStyle.italic ? FontStyle.Italic : 0) << MetadataConsts.FONT_STYLE_OFFSET;
+						metadata |= italicBit | MetadataConsts.SEMANTIC_USE_ITALIC;
+					}
+					if (typeof tokenStyle.bold !== 'undefined') {
+						const boldBit = (tokenStyle.bold ? FontStyle.Bold : 0) << MetadataConsts.FONT_STYLE_OFFSET;
+						metadata |= boldBit | MetadataConsts.SEMANTIC_USE_BOLD;
+					}
+					if (typeof tokenStyle.underline !== 'undefined') {
+						const underlineBit = (tokenStyle.underline ? FontStyle.Underline : 0) << MetadataConsts.FONT_STYLE_OFFSET;
+						metadata |= underlineBit | MetadataConsts.SEMANTIC_USE_UNDERLINE;
+					}
+					if (tokenStyle.foreground) {
+						const foregroundBits = (tokenStyle.foreground) << MetadataConsts.FOREGROUND_OFFSET;
+						metadata |= foregroundBits | MetadataConsts.SEMANTIC_USE_FOREGROUND;
+					}
+					if (metadata === 0) {
+						// Nothing!
+						metadata = SemanticTokensProviderStylingConstants.NO_STYLING;
+					}
 				}
+			} else {
+				if (this._logService.getLevel() === LogLevel.Trace) {
+					this._logService.trace(`SemanticTokensProviderStyling: unknown token type index: ${tokenTypeIndex} for legend: ${JSON.stringify(this._legend.tokenTypes)}`);
+				}
+				metadata = SemanticTokensProviderStylingConstants.NO_STYLING;
+				tokenType = 'not-in-legend';
 			}
 			this._hashTable.add(tokenTypeIndex, tokenModifierSet, languageId.id, metadata);
+
+			if (this._logService.getLevel() === LogLevel.Trace) {
+				this._logService.trace(`SemanticTokensProviderStyling ${tokenTypeIndex} (${tokenType}) / ${tokenModifierSet} (${tokenModifiers.join(' ')}): foreground ${TokenMetadata.getForeground(metadata)}, fontStyle ${TokenMetadata.getFontStyle(metadata).toString(2)}`);
+			}
 		}
-		if (this._logService.getLevel() === LogLevel.Trace) {
-			const type = this._legend.tokenTypes[tokenTypeIndex];
-			const modifiers = tokenModifierSet ? ' ' + this._legend.tokenModifiers.filter((_, i) => tokenModifierSet & (1 << i)).join(' ') : '';
-			this._logService.trace(`tokenStyleMetadata ${entry ? '[CACHED] ' : ''}${type}${modifiers}: foreground ${TokenMetadata.getForeground(metadata)}, fontStyle ${TokenMetadata.getFontStyle(metadata).toString(2)}`);
-		}
+
 		return metadata;
 	}
 }
diff --git a/src/vs/workbench/contrib/codeEditor/browser/inspectEditorTokens/inspectEditorTokens.ts b/src/vs/workbench/contrib/codeEditor/browser/inspectEditorTokens/inspectEditorTokens.ts
index 3f5ac4d934e..4eed83f9e01 100644
--- a/src/vs/workbench/contrib/codeEditor/browser/inspectEditorTokens/inspectEditorTokens.ts
+++ b/src/vs/workbench/contrib/codeEditor/browser/inspectEditorTokens/inspectEditorTokens.ts
@@ -514,8 +514,18 @@ class InspectEditorTokensWidget extends Disposable implements IContentWidget {
 			const line = lastLine + lineDelta; // 0-based
 			const character = lineDelta === 0 ? lastCharacter + charDelta : charDelta; // 0-based
 			if (posLine === line && character <= posCharacter && posCharacter < character + len) {
-				const type = semanticTokens.legend.tokenTypes[typeIdx];
-				const modifiers = semanticTokens.legend.tokenModifiers.filter((_, k) => modSet & 1 << k);
+				const type = semanticTokens.legend.tokenTypes[typeIdx] || 'not in legend (ignored)';
+				const modifiers = [];
+				let modifierSet = modSet;
+				for (let modifierIndex = 0; modifierSet > 0 && modifierIndex < semanticTokens.legend.tokenModifiers.length; modifierIndex++) {
+					if (modifierSet & 1) {
+						modifiers.push(semanticTokens.legend.tokenModifiers[modifierIndex]);
+					}
+					modifierSet = modifierSet >> 1;
+				}
+				if (modifierSet > 0) {
+					modifiers.push('not in legend (ignored)');
+				}
 				const range = new Range(line + 1, character + 1, line + 1, character + 1 + len);
 				const definitions = {};
 				const colorMap = this._themeService.getColorTheme().tokenColorMap;