Running into issue with SPFX recently Cannot redefine non-configurable property 'startsWith'

[DusteJ]

I am running into below issue when I try configuring SPFX control on Modern Page, this particular control was working fine without any issue up until now.

Something went wrong

If the problem persists, contact the site administrator and give them the information in Technical Details.

Technical Details

[SPLoaderError.loadComponentError]:
***Failed to load component "11111111-2017-4bc3-9a39-18dfdd167e1b" (DocumentNavigationWebPart).
Original error: ***Failed to load entry point from component "11111111-2017-4bc3-9a39-18dfdd167e1b" (DocumentNavigationWebPart).
Original error: Error loading https://component-id.invalid/11111111-2017-4bc3-9a39-18dfdd167e1b_0.0.1
 Cannot redefine non-configurable property 'startsWith'

***INNERERROR:
***Failed to load entry point from component "11111111-2017-4bc3-9a39-18dfdd167e1b" (DocumentNavigationWebPart).
Original error: Error loading https://component-id.invalid/11111111-2017-4bc3-9a39-18dfdd167e1b_0.0.1
 Cannot redefine non-configurable property 'startsWith'
***CALLSTACK:
Error
   at t._generateErrorStackForIE (https://spoprod-a.akamaihd.net/files/sp-client-prod_2019-04-19.008/sp-webpart-workbench-assembly_en-...)
   at t (https://spoprod-a.akamaihd.net/files/sp-client-prod_2019-04-19.008/sp-webpart-workbench-assembly_en-...)
   at t (https://spoprod-a.akamaihd.net/files/sp-client-prod_2019-04-19.008/sp-webpart-workbench-assembly_en-...)
   at e.buildErrorWithVerboseLog (https://spoprod-a.akamaihd.net/files/sp-client-prod_2019-04-19.008/sp-webpart-workbench-assembly_en-...)
   at e.buildLoadComponentError (https://spoprod-a.akamaihd.net/files/sp-client-prod_2019-04-19.008/sp-webpart-workbench-assembly_en-...)
   at Anonymous function (https://spoprod-a.akamaihd.net/files/sp-client-prod_2019-04-19.008/sp-webpart-workbench-assembly_en-...)
   at L (https://spoprod-a.akamaihd.net/files/sp-client-prod_2019-04-19.008/sp-webpart-workbench-assembly_en-...)
   at T (https://spoprod-a.akamaihd.net/files/sp-client-prod_2019-04-19.008/sp-webpart-workbench-assembly_en-...)
   at O (https://spoprod-a.akamaihd.net/files/sp-client-prod_2019-04-19.008/sp-webpart-workbench-assembly_en-...)
   at g (https://spoprod-a.akamaihd.net/files/sp-client-prod_2019-04-19.008/sp-webpart-workbench-assembly_en-...)

[#2]

@DusteJ did you find a solution and a root cause?

[#3]

Same issue here. Only affects IE11. Works fine in the Workbench but our production site is down. It been working for ages, looks like Microsoft may have changed something.

[#4]

@DusteJ and @Paul Bevis we have resolved the issue in our SPFX web parts simply by removing this line:

import 'core-js/es6/string';

After an update done by Microsoft this week it seems that SharePoint Online now adds string polyfill automatically. Polyfill is used to support "old" browsers like IE11 which does not support many features of javascript.

So our conclusion is that the Issue were connected with polyfills and changes done by Microsoft this week..

[#5]

Hi @Freddy Bang 

I'm a colleague of @Paul Bevis and I've found the same line you mentioned in your reply and it worked for us so thanks a lot.

Kind regards,

Marc

[#6]

Thank you, the solution worked.