OPTIONS "consider some url" 405 (Method Not Allowed) in ionic framework

When i post some data in server, we are getting below error, kindly help solve this error. API create in DotNet.
OPTIONS “My dotnet webservice url” 405 (Method Not Allowed)
s @ polyfills.js:3
t.scheduleTask @ polyfills.js:3
onScheduleTask @ polyfills.js:3
t.scheduleTask @ polyfills.js:3
r.scheduleTask @ polyfills.js:3
r.scheduleMacroTask @ polyfills.js:3
(anonymous) @ polyfills.js:3
o.(anonymous function) @ polyfills.js:2
(anonymous) @ http.js:2364
Observable._trySubscribe @ Observable.js:172
Observable.subscribe @ Observable.js:160
subscribeToResult @ subscribeToResult.js:23
MergeMapSubscriber._innerSub @ mergeMap.js:132
MergeMapSubscriber._tryNext @ mergeMap.js:129
MergeMapSubscriber._next @ mergeMap.js:112
Subscriber.next @ Subscriber.js:93
ScalarObservable.subscribe @ ScalarObservable.js:49
Observable.trySubscribe @ Observable.js:172
Observable.subscribe @ Observable.js:160
MergeMapOperator.call @ mergeMap.js:87
Observable.subscribe @ Observable.js:157
FilterOperator.call @ filter.js:60
Observable.subscribe @ Observable.js:157
MapOperator.call @ map.js:56
Observable.subscribe @ Observable.js:157
MapOperator.call @ map.js:56
Observable.subscribe @ Observable.js:157
webpackJsonp.55.FeedbackPage.submit @ feedback.ts:75
(anonymous) @ FeedbackPage.html:81
handleEvent @ core.js:13589
callWithDebugContext @ core.js:15098
debugHandleEvent @ core.js:14685
dispatchEvent @ core.js:10004
(anonymous) @ core.js:10629
(anonymous) @ platform-browser.js:2628
t.invokeTask @ polyfills.js:3
onInvokeTask @ core.js:4751
t.invokeTask @ polyfills.js:3
r.runTask @ polyfills.js:3
e.invokeTask @ polyfills.js:3
p @ polyfills.js:2
v @ polyfills.js:2
(index):1 Failed to load “My dotnet webservice url” : Response for preflight has invalid HTTP status code 405.
core.js:1449 ERROR HttpErrorResponse {headers: HttpHeaders, status: 0, statusText: “Unknown Error”, url: null, ok: false, …}error: ProgressEvent {isTrusted: true, lengthComputable: false, loaded: 0, total: 0, type: “error”, …}headers: HttpHeaders {normalizedNames: Map(0), lazyUpdate: null, headers: Map(0)}message: "Http failure response for (unknown url): 0 Unknown Error"name: "HttpErrorResponse"ok: falsestatus: 0statusText: "Unknown Error"url: null__proto
: HttpResponseBase
defaultErrorLogger @ core.js:1449
ErrorHandler.handleError @ core.js:1510
IonicErrorHandler.handleError @ ionic-error-handler.js:61
next @ core.js:5508
schedulerFn @ core.js:4342
SafeSubscriber.__tryOrUnsub @ Subscriber.js:242
SafeSubscriber.next @ Subscriber.js:189
Subscriber._next @ Subscriber.js:129
Subscriber.next @ Subscriber.js:93
Subject.next @ Subject.js:55
EventEmitter.emit @ core.js:4322
(anonymous) @ core.js:4782
t.invoke @ polyfills.js:3
r.run @ polyfills.js:3
NgZone.runOutsideAngular @ core.js:4708
onHandleError @ core.js:4782
t.handleError @ polyfills.js:3
r.runTask @ polyfills.js:3
e.invokeTask @ polyfills.js:3
p @ polyfills.js:2
v @ polyfills.js:2
error (async)
O @ polyfills.js:2
t.scheduleTask @ polyfills.js:3
onScheduleTask @ polyfills.js:3
t.scheduleTask @ polyfills.js:3
r.scheduleTask @ polyfills.js:3
r.scheduleEventTask @ polyfills.js:3
(anonymous) @ polyfills.js:2
(anonymous) @ http.js:2353
Observable._trySubscribe @ Observable.js:172
Observable.subscribe @ Observable.js:160
subscribeToResult @ subscribeToResult.js:23
MergeMapSubscriber._innerSub @ mergeMap.js:132
MergeMapSubscriber._tryNext @ mergeMap.js:129
MergeMapSubscriber._next @ mergeMap.js:112
Subscriber.next @ Subscriber.js:93
ScalarObservable._subscribe @ ScalarObservable.js:49
Observable._trySubscribe @ Observable.js:172
Observable.subscribe @ Observable.js:160
MergeMapOperator.call @ mergeMap.js:87
Observable.subscribe @ Observable.js:157
FilterOperator.call @ filter.js:60
Observable.subscribe @ Observable.js:157
MapOperator.call @ map.js:56
Observable.subscribe @ Observable.js:157
MapOperator.call @ map.js:56
Observable.subscribe @ Observable.js:157
webpackJsonp.55.FeedbackPage.submit @ feedback.ts:75
(anonymous) @ FeedbackPage.html:81
handleEvent @ core.js:13589
callWithDebugContext @ core.js:15098
debugHandleEvent @ core.js:14685
dispatchEvent @ core.js:10004
(anonymous) @ core.js:10629
(anonymous) @ platform-browser.js:2628
t.invokeTask @ polyfills.js:3
onInvokeTask @ core.js:4751
t.invokeTask @ polyfills.js:3
r.runTask @ polyfills.js:3
e.invokeTask @ polyfills.js:3
p @ polyfills.js:2
v @ polyfills.js:2
polyfills.js:3 XHR failed loading: OPTIONS " “My dotnet webservice url”".